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	diff --git a/src/ant.c b/src/ant.c
	index fe7ab90..e0dd553 100644
	--- a/src/ant.c
	+++ b/src/ant.c
	@@ -1,3919 +1,3968 @@
	#if defined(__GNUC__) && !defined(__clang__)
	#pragma GCC optimize("O3,inline")
	#endif

	#include <assert.h>
	#include <math.h>
	#include <stdarg.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>

	#include "ant.h"
	#include "config.h"
	#include "modules/timer.h"

	typedef uint32_t jsoff_t;

	+typedef struct {
	+ jsval_t *stack;
	+ int depth;
	+ int capacity;
	+} this_stack_t;
	+
	+static this_stack_t global_this_stack = {NULL, 0, 0};
	+
	struct js {
	jsoff_t css; // max observed C stack size
	jsoff_t lwm; // JS ram low watermark: min free ram observed
	const char *code; // currently parsed code snippet
	char errmsg[256]; // error message placeholder (increased from 33)
	const char *filename; // current filename for error reporting
	uint8_t tok; // last parsed token value
	uint8_t consumed; // indicator that last parsed token was consumed
	uint8_t flags; // execution flags, see F_* constants below
	#define F_NOEXEC 1U // parse code, but not execute
	#define F_LOOP 2U // we are inside the loop
	#define F_CALL 4U // we are inside a function call
	#define F_BREAK 8U // exit the loop
	#define F_RETURN 16U // return has been executed
	jsoff_t clen; // code snippet length
	jsoff_t pos; // current parsing position
	jsoff_t toff; // offset of the last parsed token
	jsoff_t tlen; // length of the last parsed token
	jsoff_t nogc; // entity offset to exclude from GC
	jsval_t tval; // holds last parsed numeric or string literal value
	jsval_t scope; // current scope
	- jsval_t this_val; // 'this' value for method calls
	- jsval_t caller_this; // saved 'this' from caller during function call
	+ jsval_t this_val; // 'this' value for currently executing function
	uint8_t *mem; // available JS memory
	jsoff_t size; // memory size
	jsoff_t brk; // current mem usage boundary
	jsoff_t gct; // GC threshold. if brk > gct, trigger GC
	jsoff_t maxcss; // maximum allowed C stack size usage
	void *cstk; // C stack pointer at the beginning of js_eval()
	jsval_t current_func; // currently executing function (for native closures)
	};

	enum {
	TOK_ERR, TOK_EOF, TOK_IDENTIFIER, TOK_NUMBER, TOK_STRING, TOK_SEMICOLON,
	TOK_LPAREN, TOK_RPAREN, TOK_LBRACE, TOK_RBRACE, TOK_LBRACKET, TOK_RBRACKET,
	TOK_ASYNC = 50, TOK_AWAIT, TOK_BREAK, TOK_CASE, TOK_CATCH, TOK_CLASS, TOK_CONST, TOK_CONTINUE,
	TOK_DEFAULT, TOK_DELETE, TOK_DO, TOK_ELSE, TOK_FINALLY, TOK_FOR, TOK_FUNC,
	TOK_IF, TOK_IN, TOK_INSTANCEOF, TOK_LET, TOK_NEW, TOK_RETURN, TOK_SWITCH,
	TOK_THIS, TOK_THROW, TOK_TRY, TOK_VAR, TOK_VOID, TOK_WHILE, TOK_WITH,
	TOK_YIELD, TOK_UNDEF, TOK_NULL, TOK_TRUE, TOK_FALSE,
	TOK_DOT = 100, TOK_CALL, TOK_BRACKET, TOK_POSTINC, TOK_POSTDEC, TOK_NOT, TOK_TILDA,
	TOK_TYPEOF, TOK_UPLUS, TOK_UMINUS, TOK_EXP, TOK_MUL, TOK_DIV, TOK_REM,
	TOK_OPTIONAL_CHAIN,
	TOK_PLUS, TOK_MINUS, TOK_SHL, TOK_SHR, TOK_ZSHR, TOK_LT, TOK_LE, TOK_GT,
	TOK_GE, TOK_EQ, TOK_NE, TOK_AND, TOK_XOR, TOK_OR, TOK_LAND, TOK_LOR,
	TOK_COLON, TOK_Q, TOK_ASSIGN, TOK_PLUS_ASSIGN, TOK_MINUS_ASSIGN,
	TOK_MUL_ASSIGN, TOK_DIV_ASSIGN, TOK_REM_ASSIGN, TOK_SHL_ASSIGN,
	TOK_SHR_ASSIGN, TOK_ZSHR_ASSIGN, TOK_AND_ASSIGN, TOK_XOR_ASSIGN,
	TOK_OR_ASSIGN, TOK_COMMA, TOK_TEMPLATE, TOK_ARROW,
	};

	enum {
	T_OBJ, T_PROP, T_STR, T_UNDEF, T_NULL, T_NUM,
	T_BOOL, T_FUNC, T_CODEREF, T_CFUNC, T_ERR, T_ARR, T_PROMISE
	};

	static const char *typestr(uint8_t t) {
	const char *names[] = {
	"object", "prop", "string", "undefined", "null", "number",
	"boolean", "function", "coderef", "cfunc", "err", "array", "promise"
	};

	return (t < sizeof(names) / sizeof(names[0])) ? names[t] : "??";
	}

	static jsval_t tov(double d) { union { double d; jsval_t v; } u = {d}; return u.v; }
	static double tod(jsval_t v) { union { jsval_t v; double d; } u = {v}; return u.d; }
	static jsval_t mkval(uint8_t type, uint64_t data) { return ((jsval_t) 0x7ff0U << 48U) \| ((jsval_t) (type) << 48) \| (data & 0xffffffffffffUL); }
	static bool is_nan(jsval_t v) { return (v >> 52U) == 0x7ffU; }
	static uint8_t vtype(jsval_t v) { return is_nan(v) ? ((v >> 48U) & 15U) : (uint8_t) T_NUM; }
	static size_t vdata(jsval_t v) { return (size_t) (v & ~((jsval_t) 0x7fffUL << 48U)); }
	static jsval_t mkcoderef(jsval_t off, jsoff_t len) { return mkval(T_CODEREF, (off & 0xffffffU) \| ((jsval_t)(len & 0xffffffU) << 24U)); }
	static jsoff_t coderefoff(jsval_t v) { return v & 0xffffffU; }
	static jsoff_t codereflen(jsval_t v) { return (v >> 24U) & 0xffffffU; }

	static uint8_t unhex(uint8_t c) { return (c >= '0' && c <= '9') ? (uint8_t) (c - '0') : (c >= 'a' && c <= 'f') ? (uint8_t) (c - 'W') : (c >= 'A' && c <= 'F') ? (uint8_t) (c - '7') : 0; }
	static bool is_space(int c) { return c == ' ' \|\| c == '\r' \|\| c == '\n' \|\| c == '\t' \|\| c == '\f' \|\| c == '\v'; }
	static bool is_digit(int c) { return c >= '0' && c <= '9'; }
	static bool is_xdigit(int c) { return is_digit(c) \|\| (c >= 'a' && c <= 'f') \|\| (c >= 'A' && c <= 'F'); }
	static bool is_alpha(int c) { return (c >= 'a' && c <= 'z') \|\| (c >= 'A' && c <= 'Z'); }
	static bool is_ident_begin(int c) { return c == '_' \|\| c == '$' \|\| is_alpha(c); }
	static bool is_ident_continue(int c) { return c == '_' \|\| c == '$' \|\| is_alpha(c) \|\| is_digit(c); }
	static bool is_err(jsval_t v) { return vtype(v) == T_ERR; }
	static bool is_unary(uint8_t tok) { return (tok >= TOK_POSTINC && tok <= TOK_UMINUS) \|\| tok == TOK_NOT \|\| tok == TOK_TILDA \|\| tok == TOK_TYPEOF \|\| tok == TOK_VOID; }
	static bool is_assign(uint8_t tok) { return (tok >= TOK_ASSIGN && tok <= TOK_OR_ASSIGN); }
	static void saveoff(struct js *js, jsoff_t off, jsoff_t val) { memcpy(&js->mem[off], &val, sizeof(val)); }
	static void saveval(struct js *js, jsoff_t off, jsval_t val) { memcpy(&js->mem[off], &val, sizeof(val)); }
	static jsoff_t loadoff(struct js *js, jsoff_t off) { jsoff_t v = 0; assert(js->brk <= js->size); memcpy(&v, &js->mem[off], sizeof(v)); return v; }
	static jsoff_t offtolen(jsoff_t off) { return (off >> 2) - 1; }
	static jsoff_t vstrlen(struct js *js, jsval_t v) { return offtolen(loadoff(js, (jsoff_t) vdata(v))); }
	static jsval_t loadval(struct js *js, jsoff_t off) { jsval_t v = 0; memcpy(&v, &js->mem[off], sizeof(v)); return v; }
	static jsval_t upper(struct js *js, jsval_t scope) { return mkval(T_OBJ, loadoff(js, (jsoff_t) (vdata(scope) + sizeof(jsoff_t)))); }
	static jsoff_t align32(jsoff_t v) { return ((v + 3) >> 2) << 2; }

	#define CHECKV(_v) do { if (is_err(_v)) { res = (_v); goto done; } } while (0)
	#define EXPECT(_tok, _e) do { if (next(js) != _tok) { _e; return js_mkerr(js, "parse error"); }; js->consumed = 1; } while (0)

	static bool streq(const char buf, size_t len, const char p, size_t n);
	static size_t tostr(struct js js, jsval_t value, char buf, size_t len);
	static size_t strpromise(struct js js, jsval_t value, char buf, size_t len);

	static inline jsoff_t esize(jsoff_t w);
	static jsval_t js_expr(struct js *js);
	static jsval_t js_stmt(struct js *js);
	static jsval_t js_assignment(struct js *js);
	static jsval_t js_arrow_func(struct js *js, jsoff_t params_start, jsoff_t params_end, bool is_async);
	static jsval_t do_op(struct js *, uint8_t op, jsval_t l, jsval_t r);
	static jsval_t do_instanceof(struct js *js, jsval_t l, jsval_t r);
	static jsval_t resolveprop(struct js *js, jsval_t v);
	static jsoff_t lkp(struct js js, jsval_t obj, const char buf, size_t len);
	static jsval_t builtin_array_push(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_array_pop(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_array_slice(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_array_join(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_array_includes(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_string_indexOf(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_string_substring(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_string_split(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_string_slice(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_string_includes(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_string_startsWith(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_string_endsWith(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_string_replace(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_string_template(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_string_charCodeAt(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_Object(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_Promise(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_Promise_resolve(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_Promise_reject(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_Promise_try(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_promise_then(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_promise_catch(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_promise_finally(struct js js, jsval_t args, int nargs);

	static void setlwm(struct js *js) {
	jsoff_t n = 0, css = 0;
	if (js->brk < js->size) n = js->size - js->brk;
	if (js->lwm > n) js->lwm = n;
	if ((char ) js->cstk > (char ) &n)
	css = (jsoff_t) ((char ) js->cstk - (char ) &n);
	if (css > js->css) js->css = css;
	}

	static size_t cpy(char dst, size_t dstlen, const char src, size_t srclen) {
	size_t i = 0;
	for (i = 0; i < dstlen && i < srclen && src[i] != 0; i++) dst[i] = src[i];
	if (dstlen > 0) dst[i < dstlen ? i : dstlen - 1] = '\0';
	return i;
	}

	static size_t strarr(struct js js, jsval_t obj, char buf, size_t len) {
	size_t n = cpy(buf, len, "[", 1);
	jsoff_t next = loadoff(js, (jsoff_t) vdata(obj)) & ~(3U \| CONSTMASK);
	jsoff_t length = 0;
	jsoff_t scan = next;

	while (scan < js->brk && scan != 0) {
	jsoff_t koff = loadoff(js, scan + (jsoff_t) sizeof(scan));
	jsoff_t klen = offtolen(loadoff(js, koff));
	const char key = (char ) &js->mem[koff + sizeof(koff)];

	if (streq(key, klen, "length", 6)) {
	jsval_t val = loadval(js, scan + (jsoff_t) (sizeof(scan) + sizeof(koff)));
	if (vtype(val) == T_NUM) length = (jsoff_t) tod(val);
	break;
	}
	scan = loadoff(js, scan) & ~(3U \| CONSTMASK);
	}

	for (jsoff_t i = 0; i < length; i++) {
	if (i > 0) n += cpy(buf + n, len - n, ",", 1);
	char idx[16];
	snprintf(idx, sizeof(idx), "%u", (unsigned) i);

	jsoff_t idxlen = (jsoff_t) strlen(idx);
	jsoff_t prop = next;
	jsval_t val = js_mkundef();

	bool found = false;

	while (prop < js->brk && prop != 0) {
	jsoff_t koff = loadoff(js, prop + (jsoff_t) sizeof(prop));
	jsoff_t klen = offtolen(loadoff(js, koff));
	const char key = (char ) &js->mem[koff + sizeof(koff)];
	if (streq(key, klen, idx, idxlen)) {
	val = loadval(js, prop + (jsoff_t) (sizeof(prop) + sizeof(koff)));
	found = true;
	break;
	}
	prop = loadoff(js, prop) & ~(3U \| CONSTMASK);
	}

	if (found) {
	n += tostr(js, val, buf + n, len - n);
	} else {
	n += cpy(buf + n, len - n, "undefined", 9);
	}
	}

	return n + cpy(buf + n, len - n, "]", 1);
	}

	static size_t strobj(struct js js, jsval_t obj, char buf, size_t len) {
	size_t n = cpy(buf, len, "{", 1);
	jsoff_t next = loadoff(js, (jsoff_t) vdata(obj)) & ~(3U \| CONSTMASK);

	while (next < js->brk && next != 0) {
	jsoff_t koff = loadoff(js, next + (jsoff_t) sizeof(next));
	jsval_t val = loadval(js, next + (jsoff_t) (sizeof(next) + sizeof(koff)));
	n += cpy(buf + n, len - n, ",", n == 1 ? 0 : 1);
	n += tostr(js, mkval(T_STR, koff), buf + n, len - n);
	n += cpy(buf + n, len - n, ":", 1);
	n += tostr(js, val, buf + n, len - n);
	next = loadoff(js, next) & ~(3U \| CONSTMASK);
	}

	return n + cpy(buf + n, len - n, "}", 1);
	}

	static size_t strnum(jsval_t value, char *buf, size_t len) {
	double dv = tod(value), iv;
	const char *fmt = modf(dv, &iv) == 0.0 ? "%.17g" : "%g";
	return (size_t) snprintf(buf, len, fmt, dv);
	}

	static jsoff_t vstr(struct js js, jsval_t value, jsoff_t len) {
	jsoff_t off = (jsoff_t) vdata(value);
	if (len) *len = offtolen(loadoff(js, off));
	return (jsoff_t) (off + sizeof(off));
	}

	static size_t strstring(struct js js, jsval_t value, char buf, size_t len) {
	jsoff_t slen, off = vstr(js, value, &slen);
	size_t n = 0;
	n += cpy(buf + n, len - n, "\"", 1);
	n += cpy(buf + n, len - n, (char *) &js->mem[off], slen);
	n += cpy(buf + n, len - n, "\"", 1);

	return n;
	}

	static size_t strfunc(struct js js, jsval_t value, char buf, size_t len) {
	jsval_t func_obj = mkval(T_OBJ, vdata(value));
	jsoff_t code_off = lkp(js, func_obj, "__code", 6);

	if (code_off == 0) return cpy(buf, len, "function()", 10);
	jsval_t code_val = resolveprop(js, mkval(T_PROP, code_off));

	if (vtype(code_val) != T_STR) return cpy(buf, len, "function()", 10);
	jsoff_t sn, off = vstr(js, code_val, &sn);
	size_t n = cpy(buf, len, "function", 8);

	return n + cpy(buf + n, len - n, (char *) &js->mem[off], sn);
	}

	static void get_line_col(const char code, jsoff_t pos, int line, int *col) {
	*line = 1;
	*col = 1;
	for (jsoff_t i = 0; i < pos && code[i] != '\0'; i++) {
	if (code[i] == '\n') {
	(*line)++;
	*col = 1;
	} else {
	(*col)++;
	}
	}
	}

	static void get_error_line(const char code, jsoff_t clen, jsoff_t pos, char buf, size_t bufsize, int *line_start_col) {
	jsoff_t line_start = pos;
	while (line_start > 0 && code[line_start - 1] != '\n') {
	line_start--;
	}

	jsoff_t line_end = pos;
	while (line_end < clen && code[line_end] != '\n' && code[line_end] != '\0') {
	line_end++;
	}

	jsoff_t line_len = line_end - line_start;
	if (line_len >= bufsize) line_len = bufsize - 1;

	memcpy(buf, &code[line_start], line_len);
	buf[line_len] = '\0';
	*line_start_col = (int)(pos - line_start) + 1;
	}

	jsval_t js_mkerr(struct js js, const char xx, ...) {
	va_list ap;
	int line = 0, col = 0;
	char error_line[256] = {0};
	int error_col = 0;
	get_line_col(js->code, js->toff > 0 ? js->toff : js->pos, &line, &col);
	get_error_line(js->code, js->clen, js->toff > 0 ? js->toff : js->pos, error_line, sizeof(error_line), &error_col);
	size_t n = 0;
	if (js->filename) {
	n = (size_t) snprintf(js->errmsg, sizeof(js->errmsg), "Panic: %s:%d:%d\n", js->filename, line, col);
	} else {
	n = (size_t) snprintf(js->errmsg, sizeof(js->errmsg), "Panic: <eval>:%d:%d\n", line, col);
	}
	va_start(ap, xx);
	vsnprintf(js->errmsg + n, sizeof(js->errmsg) - n, xx, ap);
	va_end(ap);
	n = strlen(js->errmsg);
	if (n < sizeof(js->errmsg) - 1) {
	js->errmsg[n++] = '\n';
	}
	size_t remaining = sizeof(js->errmsg) - n;
	size_t added = (size_t) snprintf(js->errmsg + n, remaining, "%s\n", error_line);
	n += added;
	if (n < sizeof(js->errmsg) - 1) {
	remaining = sizeof(js->errmsg) - n;
	for (int i = 1; i < error_col && remaining > 1; i++) {
	js->errmsg[n++] = ' ';
	remaining--;
	}
	if (remaining > 3) {
	js->errmsg[n++] = '^';
	js->errmsg[n++] = '^';
	js->errmsg[n++] = '^';
	}
	js->errmsg[n] = '\0';
	}
	js->errmsg[sizeof(js->errmsg) - 1] = '\0';
	js->pos = js->clen, js->tok = TOK_EOF, js->consumed = 0;
	return mkval(T_ERR, 0);
	}

	static size_t tostr(struct js js, jsval_t value, char buf, size_t len) {
	switch (vtype(value)) {
	case T_UNDEF: return cpy(buf, len, "undefined", 9);
	case T_NULL: return cpy(buf, len, "null", 4);
	case T_BOOL: return cpy(buf, len, vdata(value) & 1 ? "true" : "false", vdata(value) & 1 ? 4 : 5);
	case T_ARR: return strarr(js, value, buf, len);
	case T_OBJ: return strobj(js, value, buf, len);
	case T_STR: return strstring(js, value, buf, len);
	case T_NUM: return strnum(value, buf, len);
	case T_PROMISE: return strpromise(js, value, buf, len);
	case T_FUNC: return strfunc(js, value, buf, len);
	case T_CFUNC: return (size_t) snprintf(buf, len, "\"c_func_0x%lx\"", (unsigned long) vdata(value));
	case T_PROP: return (size_t) snprintf(buf, len, "PROP@%lu", (unsigned long) vdata(value));
	default: return (size_t) snprintf(buf, len, "VTYPE%d", vtype(value));
	}
	}

	const char js_str(struct js js, jsval_t value) {
	char buf = (char ) &js->mem[js->brk + sizeof(jsoff_t)];
	size_t len, available = js->size - js->brk - sizeof(jsoff_t);

	if (is_err(value)) return js->errmsg;
	if (js->brk + sizeof(jsoff_t) >= js->size) return "";

	len = tostr(js, value, buf, available);
	js_mkstr(js, NULL, len);
	return buf;
	}

	bool js_truthy(struct js *js, jsval_t v) {
	uint8_t t = vtype(v);
	return (t == T_BOOL && vdata(v) != 0) \|\| (t == T_NUM && tod(v) != 0.0) \|\|
	(t == T_OBJ \|\| t == T_FUNC \|\| t == T_ARR) \|\| (t == T_STR && vstrlen(js, v) > 0);
	}

	static jsoff_t js_alloc(struct js *js, size_t size) {
	jsoff_t ofs = js->brk;
	size = align32((jsoff_t) size);
	if (js->brk + size > js->size) return ~(jsoff_t) 0;
	js->brk += (jsoff_t) size;
	return ofs;
	}

	static jsval_t mkentity(struct js js, jsoff_t b, const void buf, size_t len) {
	jsoff_t ofs = js_alloc(js, len + sizeof(b));
	if (ofs == (jsoff_t) ~0) return js_mkerr(js, "oom");
	memcpy(&js->mem[ofs], &b, sizeof(b));
	if (buf != NULL) memmove(&js->mem[ofs + sizeof(b)], buf, len);
	if ((b & 3) == T_STR) js->mem[ofs + sizeof(b) + len - 1] = 0;
	return mkval(b & 3, ofs);
	}

	jsval_t js_mkstr(struct js js, const void ptr, size_t len) {
	jsoff_t n = (jsoff_t) (len + 1);
	return mkentity(js, (jsoff_t) ((n << 2) \| T_STR), ptr, n);
	}

	static jsval_t mkobj(struct js *js, jsoff_t parent) {
	return mkentity(js, 0 \| T_OBJ, &parent, sizeof(parent));
	}

	static jsval_t mkarr(struct js *js) {
	return mkobj(js, 0);
	}

	static bool is_const_prop(struct js *js, jsoff_t propoff) {
	for (jsoff_t off = 0; off < js->brk;) {
	jsoff_t v = loadoff(js, off);
	jsoff_t n = esize(v & ~(GCMASK \| CONSTMASK));
	jsoff_t cleaned = v & ~(GCMASK \| CONSTMASK);
	if ((cleaned & 3) == T_OBJ) {
	jsoff_t firstprop = cleaned & ~3U;
	if (firstprop == propoff && (v & CONSTMASK)) {
	return true;
	}
	} else if ((cleaned & 3) == T_PROP) {
	jsoff_t nextprop = cleaned & ~3U;
	if (nextprop == propoff && (v & CONSTMASK)) {
	return true;
	}
	}
	off += n;
	}
	return false;
	}

	static jsval_t mkprop(struct js *js, jsval_t obj, jsval_t k, jsval_t v, bool is_const) {
	jsoff_t koff = (jsoff_t) vdata(k);
	jsoff_t b, head = (jsoff_t) vdata(obj);
	char buf[sizeof(koff) + sizeof(v)];
	memcpy(&b, &js->mem[head], sizeof(b));
	memcpy(buf, &koff, sizeof(koff));
	memcpy(buf + sizeof(koff), &v, sizeof(v));
	jsoff_t brk = js->brk \| T_OBJ;
	if (is_const) brk \|= CONSTMASK;
	memcpy(&js->mem[head], &brk, sizeof(brk));
	return mkentity(js, (b & ~(3U \| CONSTMASK)) \| T_PROP, buf, sizeof(buf));
	}

	static jsval_t setprop(struct js *js, jsval_t obj, jsval_t k, jsval_t v) {
	jsoff_t koff = (jsoff_t) vdata(k);
	jsoff_t klen = offtolen(loadoff(js, koff));
	const char key = (char ) &js->mem[koff + sizeof(jsoff_t)];
	jsoff_t existing = lkp(js, obj, key, klen);
	if (existing > 0) {
	if (is_const_prop(js, existing)) {
	return js_mkerr(js, "assignment to constant");
	}
	saveval(js, existing + sizeof(jsoff_t) * 2, v);
	return mkval(T_PROP, existing);
	}
	return mkprop(js, obj, k, v, false);
	}

	static inline jsoff_t esize(jsoff_t w) {
	jsoff_t cleaned = w & ~(GCMASK \| CONSTMASK);
	switch (cleaned & 3U) {
	case T_OBJ: return (jsoff_t) (sizeof(jsoff_t) + sizeof(jsoff_t));
	case T_PROP: return (jsoff_t) (sizeof(jsoff_t) + sizeof(jsoff_t) + sizeof(jsval_t));
	case T_STR: return (jsoff_t) (sizeof(jsoff_t) + align32(cleaned >> 2U));
	default: return (jsoff_t) ~0U;
	}
	}

	static bool is_mem_entity(uint8_t t) {
	return t == T_OBJ \|\| t == T_PROP \|\| t == T_STR \|\| t == T_FUNC \|\| t == T_ARR \|\| t == T_PROMISE;
	}

	static void js_fixup_offsets(struct js *js, jsoff_t start, jsoff_t size) {
	for (jsoff_t n, v, off = 0; off < js->brk; off += n) {
	v = loadoff(js, off);
	n = esize(v & ~(GCMASK \| CONSTMASK));
	if (v & GCMASK) continue;

	jsoff_t flags = v & (GCMASK \| CONSTMASK);
	jsoff_t cleaned = v & ~(GCMASK \| CONSTMASK);
	if ((cleaned & 3) != T_OBJ && (cleaned & 3) != T_PROP) continue;
	jsoff_t adjusted = cleaned > start ? cleaned - size : cleaned;
	if (cleaned != adjusted) saveoff(js, off, adjusted \| flags);
	if ((cleaned & 3) == T_OBJ) {
	jsoff_t u = loadoff(js, (jsoff_t) (off + sizeof(jsoff_t)));
	if (u > start) saveoff(js, (jsoff_t) (off + sizeof(jsoff_t)), u - size);
	}
	if ((cleaned & 3) == T_PROP) {
	jsoff_t koff = loadoff(js, (jsoff_t) (off + sizeof(off)));
	if (koff > start) saveoff(js, (jsoff_t) (off + sizeof(off)), koff - size);
	jsval_t val = loadval(js, (jsoff_t) (off + sizeof(off) + sizeof(off)));
	if (is_mem_entity(vtype(val)) && vdata(val) > start) {
	saveval(js, (jsoff_t) (off + sizeof(off) + sizeof(off)), mkval(vtype(val), (unsigned long) (vdata(val) - size)));
	}
	}
	}

	jsoff_t off = (jsoff_t) vdata(js->scope);
	if (off > start) js->scope = mkval(T_OBJ, off - size);
	if (js->nogc >= start) js->nogc -= size;
	if (js->code > (char ) js->mem && js->code - (char ) js->mem < js->size && js->code - (char *) js->mem > start) {
	js->code -= size;
	}
	}

	static void js_delete_marked_entities(struct js *js) {
	for (jsoff_t n, v, off = 0; off < js->brk; off += n) {
	v = loadoff(js, off);
	n = esize(v & ~(GCMASK \| CONSTMASK));
	if (v & GCMASK) {
	js_fixup_offsets(js, off, n);
	memmove(&js->mem[off], &js->mem[off + n], js->brk - off - n);
	js->brk -= n;
	n = 0;
	}
	}
	}

	static void js_mark_all_entities_for_deletion(struct js *js) {
	for (jsoff_t v, off = 0; off < js->brk; off += esize(v & ~(GCMASK \| CONSTMASK))) {
	v = loadoff(js, off);
	saveoff(js, off, v \| GCMASK);
	}
	}

	static jsoff_t js_unmark_entity(struct js *js, jsoff_t off) {
	jsoff_t v = loadoff(js, off);
	if (v & GCMASK) {
	saveoff(js, off, v & ~GCMASK);
	jsoff_t cleaned = v & ~(GCMASK \| CONSTMASK);
	if ((cleaned & 3) == T_OBJ) js_unmark_entity(js, cleaned & ~3);
	if ((cleaned & 3) == T_PROP) {
	js_unmark_entity(js, cleaned & ~3);
	js_unmark_entity(js, loadoff(js, (jsoff_t) (off + sizeof(off))));
	jsval_t val = loadval(js, (jsoff_t) (off + sizeof(off) + sizeof(off)));
	if (is_mem_entity(vtype(val))) js_unmark_entity(js, (jsoff_t) vdata(val));
	}
	}
	return v & ~(GCMASK \| CONSTMASK \| 3U);
	}

	static void js_unmark_used_entities(struct js *js) {
	jsval_t scope = js->scope;
	do {
	js_unmark_entity(js, (jsoff_t) vdata(scope));
	scope = upper(js, scope);
	} while (vdata(scope) != 0);
	if (js->nogc) js_unmark_entity(js, js->nogc);
	}

	void js_gc(struct js *js) {
	setlwm(js);
	if (js->nogc == (jsoff_t) ~0) return;
	js_mark_all_entities_for_deletion(js);
	js_unmark_used_entities(js);
	js_delete_marked_entities(js);
	}

	static jsoff_t skiptonext(const char *code, jsoff_t len, jsoff_t n) {
	while (n < len) {
	if (is_space(code[n])) {
	n++;
	} else if (n + 1 < len && code[n] == '/' && code[n + 1] == '/') {
	for (n += 2; n < len && code[n] != '\n';) n++;
	} else if (n + 3 < len && code[n] == '/' && code[n + 1] == '*') {
	for (n += 4; n < len && (code[n - 2] != '*' \|\| code[n - 1] != '/');) n++;
	} else {
	break;
	}
	}
	return n;
	}

	static bool streq(const char buf, size_t len, const char p, size_t n) {
	return n == len && memcmp(buf, p, len) == 0;
	}

	static uint8_t parsekeyword(const char *buf, size_t len) {
	switch (buf[0]) {
	case 'a': if (streq("async", 5, buf, len)) return TOK_ASYNC; if (streq("await", 5, buf, len)) return TOK_AWAIT; break;
	case 'b': if (streq("break", 5, buf, len)) return TOK_BREAK; break;
	case 'c': if (streq("class", 5, buf, len)) return TOK_CLASS; if (streq("case", 4, buf, len)) return TOK_CASE; if (streq("catch", 5, buf, len)) return TOK_CATCH; if (streq("const", 5, buf, len)) return TOK_CONST; if (streq("continue", 8, buf, len)) return TOK_CONTINUE; break;
	case 'd': if (streq("do", 2, buf, len)) return TOK_DO; if (streq("default", 7, buf, len)) return TOK_DEFAULT; if (streq("delete", 6, buf, len)) return TOK_DELETE; break;
	case 'e': if (streq("else", 4, buf, len)) return TOK_ELSE; break;
	case 'f': if (streq("for", 3, buf, len)) return TOK_FOR; if (streq("function", 8, buf, len)) return TOK_FUNC; if (streq("finally", 7, buf, len)) return TOK_FINALLY; if (streq("false", 5, buf, len)) return TOK_FALSE; break;
	case 'i': if (streq("if", 2, buf, len)) return TOK_IF; if (streq("in", 2, buf, len)) return TOK_IN; if (streq("instanceof", 10, buf, len)) return TOK_INSTANCEOF; break;
	case 'l': if (streq("let", 3, buf, len)) return TOK_LET; break;
	case 'n': if (streq("new", 3, buf, len)) return TOK_NEW; if (streq("null", 4, buf, len)) return TOK_NULL; break;
	case 'r': if (streq("return", 6, buf, len)) return TOK_RETURN; break;
	case 's': if (streq("switch", 6, buf, len)) return TOK_SWITCH; break;
	case 't': if (streq("try", 3, buf, len)) return TOK_TRY; if (streq("this", 4, buf, len)) return TOK_THIS; if (streq("throw", 5, buf, len)) return TOK_THROW; if (streq("true", 4, buf, len)) return TOK_TRUE; if (streq("typeof", 6, buf, len)) return TOK_TYPEOF; break;
	case 'u': if (streq("undefined", 9, buf, len)) return TOK_UNDEF; break;
	case 'v': if (streq("var", 3, buf, len)) return TOK_VAR; if (streq("void", 4, buf, len)) return TOK_VOID; break;
	case 'w': if (streq("while", 5, buf, len)) return TOK_WHILE; if (streq("with", 4, buf, len)) return TOK_WITH; break;
	case 'y': if (streq("yield", 5, buf, len)) return TOK_YIELD; break;
	}
	return TOK_IDENTIFIER;
	}

	static uint8_t parseident(const char buf, jsoff_t len, jsoff_t tlen) {
	if (is_ident_begin(buf[0])) {
	while (tlen < len && is_ident_continue(buf[tlen])) (*tlen)++;
	return parsekeyword(buf, *tlen);
	}
	return TOK_ERR;
	}

	static uint8_t next(struct js *js) {
	if (js->consumed == 0) return js->tok;

	js->consumed = 0;
	js->tok = TOK_ERR;
	js->toff = js->pos = skiptonext(js->code, js->clen, js->pos);
	js->tlen = 0;

	const char *buf = js->code + js->toff;
	if (js->toff >= js->clen) { js->tok = TOK_EOF; return js->tok; }

	#define TOK(T, LEN) { js->tok = T; js->tlen = (LEN); break; }
	#define LOOK(OFS, CH) js->toff + OFS < js->clen && buf[OFS] == CH

	switch (buf[0]) {
	case '?': if (LOOK(1, '.')) TOK(TOK_OPTIONAL_CHAIN, 2); TOK(TOK_Q, 1);
	case ':': TOK(TOK_COLON, 1);
	case '(': TOK(TOK_LPAREN, 1);
	case ')': TOK(TOK_RPAREN, 1);
	case '{': TOK(TOK_LBRACE, 1);
	case '}': TOK(TOK_RBRACE, 1);
	case '[': TOK(TOK_LBRACKET, 1);
	case ']': TOK(TOK_RBRACKET, 1);
	case ';': TOK(TOK_SEMICOLON, 1);
	case ',': TOK(TOK_COMMA, 1);
	case '!': if (LOOK(1, '=') && LOOK(2, '=')) TOK(TOK_NE, 3); if (LOOK(1, '=')) TOK(TOK_NE, 2); TOK(TOK_NOT, 1);
	case '.': TOK(TOK_DOT, 1);
	case '~': TOK(TOK_TILDA, 1);
	case '-': if (LOOK(1, '-')) TOK(TOK_POSTDEC, 2); if (LOOK(1, '=')) TOK(TOK_MINUS_ASSIGN, 2); TOK(TOK_MINUS, 1);
	case '+': if (LOOK(1, '+')) TOK(TOK_POSTINC, 2); if (LOOK(1, '=')) TOK(TOK_PLUS_ASSIGN, 2); TOK(TOK_PLUS, 1);
	case '': if (LOOK(1, '')) TOK(TOK_EXP, 2); if (LOOK(1, '=')) TOK(TOK_MUL_ASSIGN, 2); TOK(TOK_MUL, 1);
	case '/': if (LOOK(1, '=')) TOK(TOK_DIV_ASSIGN, 2); TOK(TOK_DIV, 1);
	case '%': if (LOOK(1, '=')) TOK(TOK_REM_ASSIGN, 2); TOK(TOK_REM, 1);
	case '&': if (LOOK(1, '&')) TOK(TOK_LAND, 2); if (LOOK(1, '=')) TOK(TOK_AND_ASSIGN, 2); TOK(TOK_AND, 1);
	case '\|': if (LOOK(1, '\|')) TOK(TOK_LOR, 2); if (LOOK(1, '=')) TOK(TOK_OR_ASSIGN, 2); TOK(TOK_OR, 1);
	case '=': if (LOOK(1, '=') && LOOK(2, '=')) TOK(TOK_EQ, 3); if (LOOK(1, '=')) TOK(TOK_EQ, 2); if (LOOK(1, '>')) TOK(TOK_ARROW, 2); TOK(TOK_ASSIGN, 1);
	case '<': if (LOOK(1, '<') && LOOK(2, '=')) TOK(TOK_SHL_ASSIGN, 3); if (LOOK(1, '<')) TOK(TOK_SHL, 2); if (LOOK(1, '=')) TOK(TOK_LE, 2); TOK(TOK_LT, 1);
	case '>': if (LOOK(1, '>') && LOOK(2, '=')) TOK(TOK_SHR_ASSIGN, 3); if (LOOK(1, '>')) TOK(TOK_SHR, 2); if (LOOK(1, '=')) TOK(TOK_GE, 2); TOK(TOK_GT, 1);
	case '^': if (LOOK(1, '=')) TOK(TOK_XOR_ASSIGN, 2); TOK(TOK_XOR, 1);
	case '`':
	js->tlen++;
	while (js->toff + js->tlen < js->clen && buf[js->tlen] != '`') {
	uint8_t increment = 1;
	if (buf[js->tlen] == '\\') {
	if (js->toff + js->tlen + 2 > js->clen) break;
	increment = 2;
	}
	js->tlen += increment;
	}
	if (buf[js->tlen] == '`') js->tok = TOK_TEMPLATE, js->tlen++;
	break;
	case '"': case '\'':
	js->tlen++;
	while (js->toff + js->tlen < js->clen && buf[js->tlen] != buf[0]) {
	uint8_t increment = 1;
	if (buf[js->tlen] == '\\') {
	if (js->toff + js->tlen + 2 > js->clen) break;
	increment = 2;
	if (buf[js->tlen + 1] == 'x') {
	if (js->toff + js->tlen + 4 > js->clen) break;
	increment = 4;
	}
	}
	js->tlen += increment;
	}
	if (buf[0] == buf[js->tlen]) js->tok = TOK_STRING, js->tlen++;
	break;
	case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': {
	char *end;
	js->tval = tov(strtod(buf, &end));
	TOK(TOK_NUMBER, (jsoff_t) (end - buf));
	}
	default: js->tok = parseident(buf, js->clen - js->toff, &js->tlen); break;
	}

	js->pos = js->toff + js->tlen;
	return js->tok;
	}

	static inline uint8_t lookahead(struct js *js) {
	uint8_t old = js->tok, tok = 0;
	uint8_t old_consumed = js->consumed;
	jsoff_t pos = js->pos;

	js->consumed = 1;
	tok = next(js);
	js->pos = pos;
	js->tok = old;
	js->consumed = old_consumed;

	return tok;
	}

	void js_mkscope(struct js *js) {
	assert((js->flags & F_NOEXEC) == 0);
	jsoff_t prev = (jsoff_t) vdata(js->scope);
	js->scope = mkobj(js, prev);
	}

	void js_delscope(struct js *js) {
	js->scope = upper(js, js->scope);
	}

	static void mkscope(struct js *js) { js_mkscope(js); }
	static void delscope(struct js *js) { js_delscope(js); }

	+static inline bool push_this(jsval_t this_value) {
	+ if (global_this_stack.depth >= global_this_stack.capacity) {
	+ int new_capacity = global_this_stack.capacity == 0 ? 16 : global_this_stack.capacity * 2;
	+ jsval_t new_stack = (jsval_t ) realloc(global_this_stack.stack, new_capacity * sizeof(jsval_t));
	+ if (!new_stack) return false;
	+ global_this_stack.stack = new_stack;
	+ global_this_stack.capacity = new_capacity;
	+ }
	+ global_this_stack.stack[global_this_stack.depth++] = this_value;
	+ return true;
	+}
	+
	+static inline jsval_t pop_this() {
	+ if (global_this_stack.depth > 0) {
	+ return global_this_stack.stack[--global_this_stack.depth];
	+ }
	+ return js_mkundef();
	+}
	+
	+static inline jsval_t peek_this() {
	+ if (global_this_stack.depth > 0) {
	+ return global_this_stack.stack[global_this_stack.depth - 1];
	+ }
	+ return js_mkundef();
	+}
	+
	static jsval_t js_block(struct js *js, bool create_scope) {
	jsval_t res = js_mkundef();
	if (create_scope) mkscope(js);
	js->consumed = 1;
	while (next(js) != TOK_EOF && next(js) != TOK_RBRACE && !is_err(res)) {
	uint8_t t = js->tok;
	res = js_stmt(js);
	if (!is_err(res) && t != TOK_LBRACE && t != TOK_IF && t != TOK_WHILE &&
	t != TOK_FUNC && js->tok != TOK_SEMICOLON) {
	res = js_mkerr(js, "; expected");
	break;
	}
	if (js->flags & F_RETURN) break;
	}
	if (create_scope) delscope(js);
	return res;
	}

	static jsoff_t lkp(struct js js, jsval_t obj, const char buf, size_t len) {
	jsoff_t off = loadoff(js, (jsoff_t) vdata(obj)) & ~(3U \| CONSTMASK);
	while (off < js->brk && off != 0) {
	jsoff_t koff = loadoff(js, (jsoff_t) (off + sizeof(off)));
	jsoff_t klen = (loadoff(js, koff) >> 2) - 1;
	const char p = (char ) &js->mem[koff + sizeof(koff)];
	if (streq(buf, len, p, klen)) return off;
	off = loadoff(js, off) & ~(3U \| CONSTMASK);
	}
	return 0;
	}

	static jsval_t lookup(struct js js, const char buf, size_t len) {
	if (js->flags & F_NOEXEC) return 0;

	for (jsval_t scope = js->scope;;) {
	jsoff_t off = lkp(js, scope, buf, len);
	if (off != 0) return mkval(T_PROP, off);
	if (vdata(scope) == 0) break;
	scope = mkval(T_OBJ, loadoff(js, (jsoff_t) (vdata(scope) + sizeof(jsoff_t))));
	}

	return js_mkerr(js, "'%.*s' not found", (int) len, buf);
	}

	static jsval_t resolveprop(struct js *js, jsval_t v) {
	if (vtype(v) != T_PROP) return v;
	return resolveprop(js, loadval(js, (jsoff_t) (vdata(v) + sizeof(jsoff_t) * 2)));
	}

	static jsval_t assign(struct js *js, jsval_t lhs, jsval_t val) {
	jsoff_t propoff = (jsoff_t) vdata(lhs);
	if (is_const_prop(js, propoff)) {
	return js_mkerr(js, "assignment to constant");
	}
	saveval(js, (jsoff_t) ((vdata(lhs) & ~3U) + sizeof(jsoff_t) * 2), val);
	return lhs;
	}

	static jsval_t do_assign_op(struct js *js, uint8_t op, jsval_t l, jsval_t r) {
	uint8_t m[] = {
	TOK_PLUS, TOK_MINUS, TOK_MUL, TOK_DIV, TOK_REM, TOK_SHL,
	TOK_SHR, TOK_ZSHR, TOK_AND, TOK_XOR, TOK_OR
	};

	jsval_t res = do_op(js, m[op - TOK_PLUS_ASSIGN], resolveprop(js, l), r);
	return assign(js, l, res);
	}

	static jsval_t do_string_op(struct js *js, uint8_t op, jsval_t l, jsval_t r) {
	jsoff_t n1, off1 = vstr(js, l, &n1);
	jsoff_t n2, off2 = vstr(js, r, &n2);

	if (op == TOK_PLUS) {
	jsval_t res = js_mkstr(js, NULL, n1 + n2);
	if (vtype(res) == T_STR) {
	jsoff_t n, off = vstr(js, res, &n);
	memmove(&js->mem[off], &js->mem[off1], n1);
	memmove(&js->mem[off + n1], &js->mem[off2], n2);
	}

	return res;
	} else if (op == TOK_EQ) {
	bool eq = n1 == n2 && memcmp(&js->mem[off1], &js->mem[off2], n1) == 0;
	return mkval(T_BOOL, eq ? 1 : 0);
	} else if (op == TOK_NE) {
	bool eq = n1 == n2 && memcmp(&js->mem[off1], &js->mem[off2], n1) == 0;
	return mkval(T_BOOL, eq ? 0 : 1);
	} else if (op == TOK_LT \|\| op == TOK_LE \|\| op == TOK_GT \|\| op == TOK_GE) {
	jsoff_t min_len = n1 < n2 ? n1 : n2;
	int cmp = memcmp(&js->mem[off1], &js->mem[off2], min_len);

	if (cmp == 0) {
	if (n1 == n2) {
	return mkval(T_BOOL, (op == TOK_LE \|\| op == TOK_GE) ? 1 : 0);
	} else {
	cmp = (n1 < n2) ? -1 : 1;
	}
	}

	switch (op) {
	case TOK_LT: return mkval(T_BOOL, cmp < 0 ? 1 : 0);
	case TOK_LE: return mkval(T_BOOL, cmp <= 0 ? 1 : 0);
	case TOK_GT: return mkval(T_BOOL, cmp > 0 ? 1 : 0);
	case TOK_GE: return mkval(T_BOOL, cmp >= 0 ? 1 : 0);
	default: return js_mkerr(js, "bad str op");
	}
	} else {
	return js_mkerr(js, "bad str op");
	}
	}

	static jsval_t do_bracket_op(struct js *js, jsval_t l, jsval_t r) {
	jsval_t obj = resolveprop(js, l);
	jsval_t key_val = resolveprop(js, r);
	char keybuf[32];
	const char *keystr;
	size_t keylen;
	if (vtype(key_val) == T_NUM) {
	snprintf(keybuf, sizeof(keybuf), "%.0f", tod(key_val));
	keystr = keybuf;
	keylen = strlen(keybuf);
	} else if (vtype(key_val) == T_STR) {
	jsoff_t slen;
	jsoff_t off = vstr(js, key_val, &slen);
	keystr = (char *) &js->mem[off];
	keylen = slen;
	} else {
	return js_mkerr(js, "invalid index type");
	}
	if ((vtype(obj) == T_STR \|\| vtype(obj) == T_ARR) && streq(keystr, keylen, "length", 6)) {
	if (vtype(obj) == T_STR) {
	return tov(offtolen(loadoff(js, (jsoff_t) vdata(obj))));
	}
	}
	if (vtype(obj) == T_STR) {
	if (vtype(key_val) != T_NUM) {
	return js_mkerr(js, "string indices must be numbers");
	}
	double idx_d = tod(key_val);
	if (idx_d < 0 \|\| idx_d != (double)(long)idx_d) {
	return js_mkundef();
	}
	jsoff_t idx = (jsoff_t) idx_d;
	jsoff_t str_len = offtolen(loadoff(js, (jsoff_t) vdata(obj)));
	if (idx >= str_len) {
	return js_mkundef();
	}
	jsoff_t str_off = (jsoff_t) vdata(obj) + sizeof(jsoff_t);
	char ch[2] = {js->mem[str_off + idx], 0};
	return js_mkstr(js, ch, 1);
	}
	if (vtype(obj) != T_OBJ && vtype(obj) != T_ARR) {
	return js_mkerr(js, "cannot index non-object");
	}
	jsoff_t off = lkp(js, obj, keystr, keylen);
	if (off == 0) {
	jsval_t key = js_mkstr(js, keystr, keylen);
	jsval_t prop = setprop(js, obj, key, js_mkundef());
	return prop;
	}
	return mkval(T_PROP, off);
	}

	static jsval_t do_dot_op(struct js *js, jsval_t l, jsval_t r) {
	const char ptr = (char ) &js->code[coderefoff(r)];

	if (vtype(r) != T_CODEREF) return js_mkerr(js, "ident expected");
	if (vtype(l) == T_STR) {
	if (streq(ptr, codereflen(r), "length", 6)) {
	return tov(offtolen(loadoff(js, (jsoff_t) vdata(l))));
	} else if (streq(ptr, codereflen(r), "indexOf", 7)) {
	return js_mkfun(builtin_string_indexOf);
	} else if (streq(ptr, codereflen(r), "substring", 9)) {
	return js_mkfun(builtin_string_substring);
	} else if (streq(ptr, codereflen(r), "split", 5)) {
	return js_mkfun(builtin_string_split);
	} else if (streq(ptr, codereflen(r), "slice", 5)) {
	return js_mkfun(builtin_string_slice);
	} else if (streq(ptr, codereflen(r), "includes", 8)) {
	return js_mkfun(builtin_string_includes);
	} else if (streq(ptr, codereflen(r), "startsWith", 10)) {
	return js_mkfun(builtin_string_startsWith);
	} else if (streq(ptr, codereflen(r), "endsWith", 8)) {
	return js_mkfun(builtin_string_endsWith);
	} else if (streq(ptr, codereflen(r), "replace", 7)) {
	return js_mkfun(builtin_string_replace);
	} else if (streq(ptr, codereflen(r), "template", 8)) {
	return js_mkfun(builtin_string_template);
	} else if (streq(ptr, codereflen(r), "charCodeAt", 10)) {
	return js_mkfun(builtin_string_charCodeAt);
	}
	}

	if (vtype(l) == T_ARR && streq(ptr, codereflen(r), "length", 6)) {
	jsoff_t off = lkp(js, l, "length", 6);
	if (off == 0) return tov(0);
	return resolveprop(js, mkval(T_PROP, off));
	}

	if (vtype(l) == T_ARR) {
	if (streq(ptr, codereflen(r), "push", 4)) {
	return js_mkfun(builtin_array_push);
	} else if (streq(ptr, codereflen(r), "pop", 3)) {
	return js_mkfun(builtin_array_pop);
	} else if (streq(ptr, codereflen(r), "slice", 5)) {
	return js_mkfun(builtin_array_slice);
	} else if (streq(ptr, codereflen(r), "join", 4)) {
	return js_mkfun(builtin_array_join);
	} else if (streq(ptr, codereflen(r), "includes", 8)) {
	return js_mkfun(builtin_array_includes);
	}
	}

	if (vtype(l) == T_PROMISE) {
	if (streq(ptr, codereflen(r), "then", 4)) {
	return js_mkfun(builtin_promise_then);
	} else if (streq(ptr, codereflen(r), "catch", 5)) {
	return js_mkfun(builtin_promise_catch);
	} else if (streq(ptr, codereflen(r), "finally", 7)) {
	return js_mkfun(builtin_promise_finally);
	}
	}

	if (vtype(l) == T_FUNC) {
	jsval_t func_obj = mkval(T_OBJ, vdata(l));
	jsoff_t off = lkp(js, func_obj, ptr, codereflen(r));
	if (off == 0) {
	if (streq(ptr, codereflen(r), "name", 4)) {
	return js_mkstr(js, "", 0);
	}
	jsval_t key = js_mkstr(js, ptr, codereflen(r));
	jsval_t prop = setprop(js, func_obj, key, js_mkundef());
	return prop;
	}
	return mkval(T_PROP, off);
	}

	if (vtype(l) != T_OBJ && vtype(l) != T_ARR) return js_mkerr(js, "lookup in non-obj");
	jsoff_t off = lkp(js, l, ptr, codereflen(r));
	if (off == 0) {
	jsval_t key = js_mkstr(js, ptr, codereflen(r));
	jsval_t prop = setprop(js, l, key, js_mkundef());
	return prop;
	}

	return mkval(T_PROP, off);
	}

	static jsval_t do_optional_chain_op(struct js *js, jsval_t l, jsval_t r) {
	if (vtype(l) == T_NULL \|\| vtype(l) == T_UNDEF) {
	return js_mkundef();
	}
	return do_dot_op(js, l, r);
	}

	static jsval_t js_call_params(struct js *js) {
	jsoff_t pos = js->pos;
	uint8_t flags = js->flags;
	js->flags \|= F_NOEXEC;
	js->consumed = 1;

	for (bool comma = false; next(js) != TOK_EOF; comma = true) {
	if (!comma && next(js) == TOK_RPAREN) break;
	js_expr(js);
	if (next(js) == TOK_RPAREN) break;
	EXPECT(TOK_COMMA, js->flags = flags);
	}

	EXPECT(TOK_RPAREN, js->flags = flags);
	js->flags = flags;
	return mkcoderef(pos, js->pos - pos - js->tlen);
	}

	static void reverse(jsval_t *args, int nargs) {
	for (int i = 0; i < nargs / 2; i++) {
	jsval_t tmp = args[i];
	args[i] = args[nargs - i - 1], args[nargs - i - 1] = tmp;
	}
	}

	static jsval_t call_c(struct js *js,
	jsval_t (fn)(struct js , jsval_t *, int)) {
	int argc = 0;
	- jsval_t saved_caller_this = js->caller_this;
	+ jsval_t target_this = peek_this();

	while (js->pos < js->clen) {
	if (next(js) == TOK_RPAREN) break;
	jsval_t arg = resolveprop(js, js_expr(js));
	if (js->brk + sizeof(arg) > js->size) return js_mkerr(js, "call oom");
	js->size -= (jsoff_t) sizeof(arg);
	memcpy(&js->mem[js->size], &arg, sizeof(arg));
	argc++;
	if (next(js) == TOK_COMMA) js->consumed = 1;
	}

	jsval_t saved_this = js->this_val;
	- js->this_val = saved_caller_this;
	+ js->this_val = target_this;
	reverse((jsval_t *) &js->mem[js->size], argc);
	jsval_t res = fn(js, (jsval_t *) &js->mem[js->size], argc);
	js->this_val = saved_this;
	- js->caller_this = saved_caller_this;
	setlwm(js);

	js->size += (jsoff_t) sizeof(jsval_t) * (jsoff_t) argc;
	return res;
	}

	static jsval_t call_js(struct js js, const char fn, jsoff_t fnlen, jsval_t closure_scope) {
	jsoff_t fnpos = 1;
	jsval_t saved_scope = js->scope;
	+ jsval_t target_this = peek_this();
	jsoff_t parent_scope_offset;

	if (vtype(closure_scope) == T_OBJ) {
	parent_scope_offset = (jsoff_t) vdata(closure_scope);
	} else {
	parent_scope_offset = (jsoff_t) vdata(js->scope);
	}

	jsval_t function_scope = mkobj(js, parent_scope_offset);
	while (fnpos < fnlen) {
	fnpos = skiptonext(fn, fnlen, fnpos);
	if (fnpos < fnlen && fn[fnpos] == ')') break;
	jsoff_t identlen = 0;
	uint8_t tok = parseident(&fn[fnpos], fnlen - fnpos, &identlen);
	if (tok != TOK_IDENTIFIER) break;
	js->pos = skiptonext(js->code, js->clen, js->pos);
	js->consumed = 1;
	jsval_t v = js->code[js->pos] == ')' ? js_mkundef() : js_expr(js);
	setprop(js, function_scope, js_mkstr(js, &fn[fnpos], identlen), v);
	js->pos = skiptonext(js->code, js->clen, js->pos);
	if (js->pos < js->clen && js->code[js->pos] == ',') js->pos++;
	fnpos = skiptonext(fn, fnlen, fnpos + identlen);
	if (fnpos < fnlen && fn[fnpos] == ',') fnpos++;
	}

	js->scope = function_scope;
	if (fnpos < fnlen && fn[fnpos] == ')') fnpos++;
	fnpos = skiptonext(fn, fnlen, fnpos);
	if (fnpos < fnlen && fn[fnpos] == '{') fnpos++;
	size_t n = fnlen - fnpos - 1U;
	- js->this_val = js->caller_this;
	+ js->this_val = target_this;
	js->flags = F_CALL;

	jsval_t res = js_eval(js, &fn[fnpos], n);
	if (!is_err(res) && !(js->flags & F_RETURN)) res = js_mkundef();
	js->scope = saved_scope;
	return res;
	}

	static jsval_t do_call_op(struct js *js, jsval_t func, jsval_t args) {
	if (vtype(args) != T_CODEREF) return js_mkerr(js, "bad call");
	if (vtype(func) != T_FUNC && vtype(func) != T_CFUNC)
	return js_mkerr(js, "calling non-function");
	const char *code = js->code;
	jsoff_t clen = js->clen, pos = js->pos;

	js->code = &js->code[coderefoff(args)];
	js->clen = codereflen(args);
	js->pos = skiptonext(js->code, js->clen, 0);
	uint8_t tok = js->tok, flags = js->flags;
	jsoff_t nogc = js->nogc;
	jsval_t res = js_mkundef();

	if (vtype(func) == T_FUNC) {
	jsval_t func_obj = mkval(T_OBJ, vdata(func));
	jsoff_t native_off = lkp(js, func_obj, "__native_func", 13);
	if (native_off != 0) {
	jsval_t native_val = resolveprop(js, mkval(T_PROP, native_off));
	if (vtype(native_val) == T_CFUNC) {
	jsval_t saved_func = js->current_func;
	js->current_func = func;
	res = call_c(js, (jsval_t()(struct js , jsval_t *, int)) vdata(native_val));
	js->current_func = saved_func;
	}
	} else {
	jsoff_t code_off = lkp(js, func_obj, "__code", 6);
	if (code_off == 0) return js_mkerr(js, "function has no code");
	jsval_t code_val = resolveprop(js, mkval(T_PROP, code_off));
	if (vtype(code_val) != T_STR) return js_mkerr(js, "function code not string");
	jsval_t closure_scope = js_mkundef();
	jsoff_t scope_off = lkp(js, func_obj, "__scope", 7);
	if (scope_off != 0) {
	closure_scope = resolveprop(js, mkval(T_PROP, scope_off));
	}
	jsoff_t fnlen, fnoff = vstr(js, code_val, &fnlen);
	const char code_str = (const char ) (&js->mem[fnoff]);
	bool is_async = false;
	jsoff_t async_off = lkp(js, func_obj, "__async", 7);
	if (async_off != 0) {
	jsval_t async_val = resolveprop(js, mkval(T_PROP, async_off));
	is_async = vtype(async_val) == T_BOOL && vdata(async_val) == 1;
	}
	if (fnlen == 16 && memcmp(code_str, "__builtin_Object", 16) == 0) {
	res = call_c(js, builtin_Object);
	} else {
	js->nogc = (jsoff_t) (fnoff - sizeof(jsoff_t));
	res = call_js(js, code_str, fnlen, closure_scope);
	if (is_async && !is_err(res)) {
	jsval_t promise_args[] = { res };
	res = builtin_Promise_resolve(js, promise_args, 1);
	}
	}
	}
	} else {
	res = call_c(js, (jsval_t()(struct js , jsval_t *, int)) vdata(func));
	}

	js->code = code, js->clen = clen, js->pos = pos;
	js->flags = flags, js->tok = tok, js->nogc = nogc;
	js->consumed = 1;
	return res;
	}

	static jsval_t do_op(struct js *js, uint8_t op, jsval_t lhs, jsval_t rhs) {
	if (js->flags & F_NOEXEC) return 0;
	jsval_t l = resolveprop(js, lhs), r = resolveprop(js, rhs);
	setlwm(js);
	if (is_err(l)) return l;
	if (is_err(r)) return r;
	if (is_assign(op) && vtype(lhs) != T_PROP) return js_mkerr(js, "bad lhs");
	switch (op) {
	case TOK_TYPEOF: return js_mkstr(js, typestr(vtype(r)), strlen(typestr(vtype(r))));
	case TOK_VOID: return js_mkundef();
	case TOK_INSTANCEOF: return do_instanceof(js, l, r);
	case TOK_CALL: return do_call_op(js, l, r);
	case TOK_BRACKET: return do_bracket_op(js, l, rhs);
	case TOK_ASSIGN: return assign(js, lhs, r);
	case TOK_POSTINC: {
	if (vtype(lhs) != T_PROP) return js_mkerr(js, "bad lhs for ++");
	do_assign_op(js, TOK_PLUS_ASSIGN, lhs, tov(1)); return l;
	}
	case TOK_POSTDEC: {
	if (vtype(lhs) != T_PROP) return js_mkerr(js, "bad lhs for --");
	do_assign_op(js, TOK_MINUS_ASSIGN, lhs, tov(1)); return l;
	}
	case TOK_NOT: return mkval(T_BOOL, !js_truthy(js, r));
	}
	if (is_assign(op)) return do_assign_op(js, op, lhs, r);
	if (op == TOK_EQ \|\| op == TOK_NE) {
	bool eq = false;
	if (vtype(l) == vtype(r)) {
	if (vtype(l) == T_STR) {
	jsoff_t n1, off1 = vstr(js, l, &n1);
	jsoff_t n2, off2 = vstr(js, r, &n2);
	eq = n1 == n2 && memcmp(&js->mem[off1], &js->mem[off2], n1) == 0;
	} else if (vtype(l) == T_NUM) {
	eq = tod(l) == tod(r);
	} else if (vtype(l) == T_BOOL) {
	eq = vdata(l) == vdata(r);
	} else {
	eq = vdata(l) == vdata(r);
	}
	}
	return mkval(T_BOOL, op == TOK_EQ ? eq : !eq);
	}
	if (op == TOK_PLUS && (vtype(l) == T_STR \|\| vtype(r) == T_STR)) {
	jsval_t l_str = l, r_str = r;
	if (vtype(l) != T_STR) {
	const char *str = js_str(js, l);
	l_str = js_mkstr(js, str, strlen(str));
	if (is_err(l_str)) return l_str;
	}
	if (vtype(r) != T_STR) {
	const char *str = js_str(js, r);
	r_str = js_mkstr(js, str, strlen(str));
	if (is_err(r_str)) return r_str;
	}
	return do_string_op(js, op, l_str, r_str);
	}
	if (vtype(l) == T_STR && vtype(r) == T_STR) return do_string_op(js, op, l, r);
	if (is_unary(op) && vtype(r) != T_NUM) return js_mkerr(js, "type mismatch");
	if (!is_unary(op) && op != TOK_DOT && op != TOK_OPTIONAL_CHAIN && op != TOK_INSTANCEOF && (vtype(l) != T_NUM \|\| vtype(r) != T_NUM)) return js_mkerr(js, "type mismatch");

	double a = tod(l), b = tod(r);
	switch (op) {
	case TOK_DIV: return tod(r) == 0 ? js_mkerr(js, "div by zero") : tov(a / b);
	case TOK_REM: return tov(a - b * ((double) (long) (a / b)));
	case TOK_MUL: return tov(a * b);
	case TOK_PLUS: return tov(a + b);
	case TOK_MINUS: return tov(a - b);
	case TOK_XOR: return tov((double)((long) a ^ (long) b));
	case TOK_AND: return tov((double)((long) a & (long) b));
	case TOK_OR: return tov((double)((long) a \| (long) b));
	case TOK_UMINUS: return tov(-b);
	case TOK_UPLUS: return r;
	case TOK_TILDA: return tov((double)(~(long) b));
	case TOK_SHL: return tov((double)((long) a << (long) b));
	case TOK_SHR: return tov((double)((long) a >> (long) b));
	case TOK_DOT: return do_dot_op(js, l, r);
	case TOK_OPTIONAL_CHAIN: return do_optional_chain_op(js, l, r);
	case TOK_LT: return mkval(T_BOOL, a < b);
	case TOK_LE: return mkval(T_BOOL, a <= b);
	case TOK_GT: return mkval(T_BOOL, a > b);
	case TOK_GE: return mkval(T_BOOL, a >= b);
	default: return js_mkerr(js, "unknown op %d", (int) op);
	}
	}

	static jsval_t js_template_literal(struct js *js) {
	uint8_t in = (uint8_t ) &js->code[js->toff];
	size_t template_len = js->tlen;

	size_t n = 1;
	jsval_t parts[64];
	int part_count = 0;

	while (n < template_len - 1 && part_count < 64) {
	size_t part_start = n;
	while (n < template_len - 1) {
	if (in[n] == '\\' && n + 1 < template_len - 1) {
	n += 2;
	continue;
	}
	if (in[n] == '$' && n + 1 < template_len - 1 && in[n + 1] == '{') {
	break;
	}
	n++;
	}
	if (n > part_start \|\| (n == part_start && (n >= template_len - 1 \|\| in[n] != '$'))) {
	size_t part_len = n - part_start;
	uint8_t *out = &js->mem[js->brk + sizeof(jsoff_t)];
	size_t out_len = 0;

	if (js->brk + sizeof(jsoff_t) + part_len > js->size)
	return js_mkerr(js, "oom");

	for (size_t i = part_start; i < n; i++) {
	if (in[i] == '\\' && i + 1 < n) {
	i++;
	if (in[i] == 'n') out[out_len++] = '\n';
	else if (in[i] == 't') out[out_len++] = '\t';
	else if (in[i] == 'r') out[out_len++] = '\r';
	else if (in[i] == '\\') out[out_len++] = '\\';
	else if (in[i] == '`') out[out_len++] = '`';
	else out[out_len++] = in[i];
	} else {
	out[out_len++] = in[i];
	}
	}

	parts[part_count++] = js_mkstr(js, NULL, out_len);
	}

	if (n < template_len - 1 && in[n] == '$' && in[n + 1] == '{') {
	n += 2;
	size_t expr_start = n;
	int brace_count = 1;

	while (n < template_len - 1 && brace_count > 0) {
	if (in[n] == '{') brace_count++;
	else if (in[n] == '}') brace_count--;
	if (brace_count > 0) n++;
	}

	if (brace_count != 0) return js_mkerr(js, "unclosed ${");

	const char *saved_code = js->code;
	jsoff_t saved_clen = js->clen;
	jsoff_t saved_pos = js->pos;
	uint8_t saved_tok = js->tok;
	uint8_t saved_consumed = js->consumed;

	js->code = (const char *)&in[expr_start];
	js->clen = n - expr_start;
	js->pos = 0;
	js->consumed = 1;

	jsval_t expr_result = js_expr(js);

	js->code = saved_code;
	js->clen = saved_clen;
	js->pos = saved_pos;
	js->tok = saved_tok;
	js->consumed = saved_consumed;

	if (is_err(expr_result)) return expr_result;
	expr_result = resolveprop(js, expr_result);

	if (vtype(expr_result) != T_STR) {
	const char *str = js_str(js, expr_result);
	expr_result = js_mkstr(js, str, strlen(str));
	}

	parts[part_count++] = expr_result;
	n++;
	}
	}

	if (part_count == 0) return js_mkstr(js, "", 0);
	if (part_count == 1) return parts[0];

	size_t total_len = 0;
	for (int i = 0; i < part_count; i++) {
	if (vtype(parts[i]) == T_STR) {
	total_len += vstrlen(js, parts[i]);
	}
	}

	jsval_t result = js_mkstr(js, NULL, total_len);
	if (is_err(result)) return result;

	jsoff_t result_len, result_off = vstr(js, result, &result_len);
	size_t pos = 0;

	for (int i = 0; i < part_count; i++) {
	if (vtype(parts[i]) == T_STR) {
	jsoff_t part_len, part_off = vstr(js, parts[i], &part_len);
	memmove(&js->mem[result_off + pos], &js->mem[part_off], part_len);
	pos += part_len;
	}
	}

	return result;
	}

	static jsval_t js_str_literal(struct js *js) {
	uint8_t in = (uint8_t ) &js->code[js->toff];
	uint8_t *out = &js->mem[js->brk + sizeof(jsoff_t)];
	size_t n1 = 0, n2 = 0;
	if (js->brk + sizeof(jsoff_t) + js->tlen > js->size)
	return js_mkerr(js, "oom");
	while (n2++ + 2 < js->tlen) {
	if (in[n2] == '\\') {
	if (in[n2 + 1] == in[0]) {
	out[n1++] = in[0];
	} else if (in[n2 + 1] == 'n') {
	out[n1++] = '\n';
	} else if (in[n2 + 1] == 't') {
	out[n1++] = '\t';
	} else if (in[n2 + 1] == 'r') {
	out[n1++] = '\r';
	} else if (in[n2 + 1] == 'x' && is_xdigit(in[n2 + 2]) &&
	is_xdigit(in[n2 + 3])) {
	out[n1++] = (uint8_t) ((unhex(in[n2 + 2]) << 4U) \| unhex(in[n2 + 3]));
	n2 += 2;
	} else {
	return js_mkerr(js, "bad str literal");
	}
	n2++;
	} else {
	out[n1++] = ((uint8_t *) js->code)[js->toff + n2];
	}
	}
	return js_mkstr(js, NULL, n1);
	}

	static jsval_t js_arr_literal(struct js *js) {
	uint8_t exe = !(js->flags & F_NOEXEC);
	jsval_t arr = exe ? mkarr(js) : js_mkundef();
	if (is_err(arr)) return arr;

	js->consumed = 1;
	jsoff_t idx = 0;
	while (next(js) != TOK_RBRACKET) {
	jsval_t val = js_expr(js);
	if (exe) {
	if (is_err(val)) return val;
	char idxstr[16];
	snprintf(idxstr, sizeof(idxstr), "%u", (unsigned) idx);
	jsval_t key = js_mkstr(js, idxstr, strlen(idxstr));
	jsval_t res = setprop(js, arr, key, resolveprop(js, val));
	if (is_err(res)) return res;
	}
	idx++;
	if (next(js) == TOK_RBRACKET) break;
	EXPECT(TOK_COMMA, );
	}

	EXPECT(TOK_RBRACKET, );
	if (exe) {
	jsval_t len_key = js_mkstr(js, "length", 6);
	jsval_t len_val = tov((double) idx);
	jsval_t res = setprop(js, arr, len_key, len_val);
	if (is_err(res)) return res;
	arr = mkval(T_ARR, vdata(arr));
	}
	return arr;
	}

	static jsval_t js_obj_literal(struct js *js) {
	uint8_t exe = !(js->flags & F_NOEXEC);
	jsval_t obj = exe ? mkobj(js, 0) : js_mkundef();
	if (is_err(obj)) return obj;
	js->consumed = 1;

	while (next(js) != TOK_RBRACE) {
	jsval_t key = 0;
	jsoff_t id_off = 0, id_len = 0;

	if (js->tok == TOK_IDENTIFIER) {
	id_off = js->toff;
	id_len = js->tlen;
	if (exe) key = js_mkstr(js, js->code + js->toff, js->tlen);
	} else if (js->tok == TOK_STRING) {
	if (exe) key = js_str_literal(js);
	} else {
	return js_mkerr(js, "parse error");
	}
	js->consumed = 1;

	if (id_len > 0 && (next(js) == TOK_COMMA \|\| next(js) == TOK_RBRACE)) {
	jsval_t val = lookup(js, js->code + id_off, id_len);
	if (exe) {
	if (is_err(val)) return val;
	if (is_err(key)) return key;
	jsval_t res = setprop(js, obj, key, resolveprop(js, val));
	if (is_err(res)) return res;
	}
	} else {
	EXPECT(TOK_COLON, );
	jsval_t val = js_expr(js);
	if (exe) {
	if (is_err(val)) return val;
	if (is_err(key)) return key;
	jsval_t res = setprop(js, obj, key, resolveprop(js, val));
	if (is_err(res)) return res;
	}
	}

	if (next(js) == TOK_RBRACE) break;
	EXPECT(TOK_COMMA, );
	}

	EXPECT(TOK_RBRACE, );
	return obj;
	}

	static jsval_t js_func_literal(struct js *js, bool is_async) {
	uint8_t flags = js->flags;
	js->consumed = 1;
	jsoff_t name_off = 0, name_len = 0;
	if (next(js) == TOK_IDENTIFIER) {
	name_off = js->toff;
	name_len = js->tlen;
	js->consumed = 1;
	}

	EXPECT(TOK_LPAREN, js->flags = flags);
	jsoff_t pos = js->pos - 1;
	for (bool comma = false; next(js) != TOK_EOF; comma = true) {
	if (!comma && next(js) == TOK_RPAREN) break;
	EXPECT(TOK_IDENTIFIER, js->flags = flags);
	if (next(js) == TOK_RPAREN) break;
	EXPECT(TOK_COMMA, js->flags = flags);
	}

	EXPECT(TOK_RPAREN, js->flags = flags);
	EXPECT(TOK_LBRACE, js->flags = flags);
	js->consumed = 0;
	js->flags \|= F_NOEXEC;

	jsval_t res = js_block(js, false);
	if (is_err(res)) {
	js->flags = flags;
	return res;
	}
	js->flags = flags;
	jsval_t str = js_mkstr(js, &js->code[pos], js->pos - pos);
	js->consumed = 1;
	jsval_t func_obj = mkobj(js, 0);
	if (is_err(func_obj)) return func_obj;
	jsval_t code_key = js_mkstr(js, "__code", 6);
	if (is_err(code_key)) return code_key;
	jsval_t res2 = setprop(js, func_obj, code_key, str);
	if (is_err(res2)) return res2;

	if (is_async) {
	jsval_t async_key = js_mkstr(js, "__async", 7);
	if (is_err(async_key)) return async_key;
	jsval_t res_async = setprop(js, func_obj, async_key, js_mktrue());
	if (is_err(res_async)) return res_async;
	}

	if (name_len > 0) {
	jsval_t name_key = js_mkstr(js, "name", 4);
	if (is_err(name_key)) return name_key;
	jsval_t name_val = js_mkstr(js, &js->code[name_off], name_len);
	if (is_err(name_val)) return name_val;
	jsval_t res3 = setprop(js, func_obj, name_key, name_val);
	if (is_err(res3)) return res3;
	}

	if (!(flags & F_NOEXEC)) {
	jsval_t scope_key = js_mkstr(js, "__scope", 7);
	if (is_err(scope_key)) return scope_key;
	jsval_t res4 = setprop(js, func_obj, scope_key, js->scope);
	if (is_err(res4)) return res4;
	}

	return mkval(T_FUNC, (unsigned long) vdata(func_obj));
	}

	#define RTL_BINOP(_f1, _f2, _cond) \
	jsval_t res = _f1(js); \
	while (!is_err(res) && (_cond)) { \
	uint8_t op = js->tok; \
	js->consumed = 1; \
	jsval_t rhs = _f2(js); \
	if (is_err(rhs)) return rhs; \
	res = do_op(js, op, res, rhs); \
	} \
	return res;

	#define LTR_BINOP(_f, _cond) \
	jsval_t res = _f(js); \
	while (!is_err(res) && (_cond)) { \
	uint8_t op = js->tok; \
	js->consumed = 1; \
	jsval_t rhs = _f(js); \
	if (is_err(rhs)) return rhs; \
	res = do_op(js, op, res, rhs); \
	} \
	return res;

	static jsval_t js_literal(struct js *js) {
	next(js);
	setlwm(js);
	if (js->maxcss > 0 && js->css > js->maxcss) return js_mkerr(js, "C stack");
	js->consumed = 1;

	switch (js->tok) {
	case TOK_ERR: return js_mkerr(js, "parse error");
	case TOK_NUMBER: return js->tval;
	case TOK_STRING: return js_str_literal(js);
	case TOK_TEMPLATE: return js_template_literal(js);
	case TOK_LBRACE: return js_obj_literal(js);
	case TOK_LBRACKET: return js_arr_literal(js);
	case TOK_FUNC: return js_func_literal(js, false);
	case TOK_ASYNC: {
	js->consumed = 1;
	uint8_t next_tok = next(js);
	if (next_tok == TOK_FUNC) {
	return js_func_literal(js, true);
	} else if (next_tok == TOK_LPAREN) {
	jsoff_t paren_start = js->pos - 1;
	js->consumed = 1;
	jsoff_t saved_pos = js->pos;
	uint8_t saved_tok = js->tok;
	uint8_t saved_consumed = js->consumed;
	uint8_t saved_flags = js->flags;
	int paren_depth = 1;
	js->flags \|= F_NOEXEC;
	while (paren_depth > 0 && next(js) != TOK_EOF) {
	if (js->tok == TOK_LPAREN) paren_depth++;
	else if (js->tok == TOK_RPAREN) paren_depth--;
	js->consumed = 1;
	}
	jsoff_t paren_end = js->pos;
	bool is_arrow = lookahead(js) == TOK_ARROW;
	js->pos = saved_pos;
	js->tok = saved_tok;
	js->consumed = saved_consumed;
	js->flags = saved_flags;
	if (is_arrow) {
	js->flags \|= F_NOEXEC;
	while (next(js) != TOK_RPAREN && next(js) != TOK_EOF) {
	js->consumed = 1;
	}
	if (next(js) != TOK_RPAREN) return js_mkerr(js, ") expected");
	js->consumed = 1;
	js->flags = saved_flags;
	if (next(js) != TOK_ARROW) return js_mkerr(js, "=> expected");
	js->consumed = 1;
	return js_arrow_func(js, paren_start, paren_end, true);
	}
	return js_mkerr(js, "async ( must be arrow function");
	} else if (next_tok == TOK_IDENTIFIER) {
	jsoff_t id_start = js->toff;
	jsoff_t id_len = js->tlen;
	js->consumed = 1;
	if (next(js) == TOK_ARROW) {
	js->consumed = 1;
	char param_buf[256];
	if (id_len + 3 > sizeof(param_buf)) return js_mkerr(js, "param too long");
	param_buf[0] = '(';
	memcpy(param_buf + 1, &js->code[id_start], id_len);
	param_buf[id_len + 1] = ')';
	param_buf[id_len + 2] = '\0';
	uint8_t flags = js->flags;
	bool is_expr = next(js) != TOK_LBRACE;
	jsoff_t body_start = is_expr ? js->toff : js->pos;
	jsval_t body_result;
	if (is_expr) {
	js->flags \|= F_NOEXEC;
	body_result = js_assignment(js);
	if (is_err(body_result)) { js->flags = flags; return body_result; }
	} else {
	js->flags \|= F_NOEXEC;
	js->consumed = 1;
	body_result = js_block(js, false);
	if (is_err(body_result)) { js->flags = flags; return body_result; }
	if (next(js) == TOK_RBRACE) js->consumed = 1;
	}
	js->flags = flags;
	jsoff_t body_end = js->pos;
	size_t fn_size = id_len + (body_end - body_start) + 64;
	char fn_str = (char ) malloc(fn_size);
	if (!fn_str) return js_mkerr(js, "oom");
	jsoff_t fn_pos = 0;
	memcpy(fn_str + fn_pos, param_buf, id_len + 2);
	fn_pos += id_len + 2;
	fn_str[fn_pos++] = '{';
	if (is_expr) {
	memcpy(fn_str + fn_pos, "return ", 7);
	fn_pos += 7;
	size_t body_len = body_end - body_start;
	memcpy(fn_str + fn_pos, &js->code[body_start], body_len);
	fn_pos += body_len;
	} else {
	size_t body_len = body_end - body_start - 2;
	memcpy(fn_str + fn_pos, &js->code[body_start + 1], body_len);
	fn_pos += body_len;
	}
	fn_str[fn_pos++] = '}';
	jsval_t str = js_mkstr(js, fn_str, fn_pos);
	free(fn_str);
	if (is_err(str)) return str;
	jsval_t func_obj = mkobj(js, 0);
	if (is_err(func_obj)) return func_obj;
	jsval_t code_key = js_mkstr(js, "__code", 6);
	if (is_err(code_key)) return code_key;
	jsval_t res = setprop(js, func_obj, code_key, str);
	if (is_err(res)) return res;
	jsval_t async_key = js_mkstr(js, "__async", 7);
	if (is_err(async_key)) return async_key;
	jsval_t res_async = setprop(js, func_obj, async_key, js_mktrue());
	if (is_err(res_async)) return res_async;
	if (!(flags & F_NOEXEC)) {
	jsval_t scope_key = js_mkstr(js, "__scope", 7);
	if (is_err(scope_key)) return scope_key;
	jsval_t res2 = setprop(js, func_obj, scope_key, js->scope);
	if (is_err(res2)) return res2;
	}
	return mkval(T_FUNC, (unsigned long) vdata(func_obj));
	}
	return mkcoderef((jsoff_t) id_start, (jsoff_t) id_len);
	}
	return js_mkerr(js, "unexpected token after async");
	}
	case TOK_NULL: return js_mknull();
	case TOK_UNDEF: return js_mkundef();
	case TOK_TRUE: return js_mktrue();
	case TOK_FALSE: return js_mkfalse();
	case TOK_THIS: return js->this_val;
	case TOK_IDENTIFIER: return mkcoderef((jsoff_t) js->toff, (jsoff_t) js->tlen);
	case TOK_CATCH: return mkcoderef((jsoff_t) js->toff, (jsoff_t) js->tlen);
	case TOK_TRY: return mkcoderef((jsoff_t) js->toff, (jsoff_t) js->tlen);
	case TOK_FINALLY: return mkcoderef((jsoff_t) js->toff, (jsoff_t) js->tlen);
	default: return js_mkerr(js, "bad expr");
	}
	}

	static jsval_t js_arrow_func(struct js *js, jsoff_t params_start, jsoff_t params_end, bool is_async) {
	uint8_t flags = js->flags;
	bool is_expr = next(js) != TOK_LBRACE;
	jsoff_t body_start, body_end_actual;
	jsval_t body_result;

	if (is_expr) {
	body_start = js->toff;
	js->flags \|= F_NOEXEC;
	body_result = js_assignment(js);
	if (is_err(body_result)) {
	js->flags = flags;
	return body_result;
	}
	uint8_t tok = next(js);
	if (tok == TOK_RPAREN \|\| tok == TOK_RBRACE \|\| tok == TOK_SEMICOLON \|\|
	tok == TOK_COMMA \|\| tok == TOK_EOF) {
	body_end_actual = js->toff;
	} else {
	body_end_actual = js->pos;
	}
	} else {
	body_start = js->toff;
	js->flags \|= F_NOEXEC;
	js->consumed = 1;
	body_result = js_block(js, false);
	if (is_err(body_result)) {
	js->flags = flags;
	return body_result;
	}
	if (next(js) == TOK_RBRACE) {
	body_end_actual = js->toff;
	js->consumed = 1;
	} else {
	body_end_actual = js->pos;
	}
	}

	js->flags = flags;

	size_t fn_size = (params_end - params_start) + (body_end_actual - body_start) + 32;
	char fn_str = (char ) malloc(fn_size);
	if (!fn_str) return js_mkerr(js, "oom");

	jsoff_t fn_pos = 0;

	size_t param_len = params_end - params_start;
	memcpy(fn_str + fn_pos, &js->code[params_start], param_len);
	fn_pos += param_len;

	fn_str[fn_pos++] = '{';

	if (is_expr) {
	memcpy(fn_str + fn_pos, "return ", 7);
	fn_pos += 7;
	size_t body_len = body_end_actual - body_start;
	memcpy(fn_str + fn_pos, &js->code[body_start], body_len);
	fn_pos += body_len;
	} else {
	size_t body_len = body_end_actual - body_start - 1;
	memcpy(fn_str + fn_pos, &js->code[body_start + 1], body_len);
	fn_pos += body_len;
	}

	fn_str[fn_pos++] = '}';

	jsval_t str = js_mkstr(js, fn_str, fn_pos);
	free(fn_str);
	if (is_err(str)) return str;

	jsval_t func_obj = mkobj(js, 0);
	if (is_err(func_obj)) return func_obj;

	jsval_t code_key = js_mkstr(js, "__code", 6);
	if (is_err(code_key)) return code_key;

	jsval_t res = setprop(js, func_obj, code_key, str);
	if (is_err(res)) return res;

	if (is_async) {
	jsval_t async_key = js_mkstr(js, "__async", 7);
	if (is_err(async_key)) return async_key;
	jsval_t res_async = setprop(js, func_obj, async_key, js_mktrue());
	if (is_err(res_async)) return res_async;
	}

	if (!(flags & F_NOEXEC)) {
	jsval_t scope_key = js_mkstr(js, "__scope", 7);
	if (is_err(scope_key)) return scope_key;
	jsval_t res2 = setprop(js, func_obj, scope_key, js->scope);
	if (is_err(res2)) return res2;
	}

	return mkval(T_FUNC, (unsigned long) vdata(func_obj));
	}

	static jsval_t js_group(struct js *js) {
	if (next(js) == TOK_LPAREN) {
	jsoff_t paren_start = js->pos - 1;
	js->consumed = 1;

	jsoff_t saved_pos = js->pos;
	uint8_t saved_tok = js->tok;
	uint8_t saved_consumed = js->consumed;
	uint8_t saved_flags = js->flags;

	int paren_depth = 1;
	bool could_be_arrow = true;
	js->flags \|= F_NOEXEC;

	while (paren_depth > 0 && next(js) != TOK_EOF) {
	if (js->tok == TOK_LPAREN) paren_depth++;
	else if (js->tok == TOK_RPAREN) paren_depth--;

	if (paren_depth > 0) {
	if (js->tok != TOK_IDENTIFIER && js->tok != TOK_COMMA) could_be_arrow = false;
	}
	js->consumed = 1;
	}

	jsoff_t paren_end = js->pos;
	bool is_arrow = could_be_arrow && lookahead(js) == TOK_ARROW;

	js->pos = saved_pos;
	js->tok = saved_tok;
	js->consumed = saved_consumed;
	js->flags = saved_flags;

	if (is_arrow) {
	js->flags \|= F_NOEXEC;
	while (next(js) != TOK_RPAREN && next(js) != TOK_EOF) {
	js->consumed = 1;
	}
	if (next(js) != TOK_RPAREN) return js_mkerr(js, ") expected");
	js->consumed = 1;
	js->flags = saved_flags;

	if (next(js) != TOK_ARROW) return js_mkerr(js, "=> expected");
	js->consumed = 1;

	return js_arrow_func(js, paren_start, paren_end, false);
	} else {
	jsval_t v = js_expr(js);
	if (is_err(v)) return v;
	if (next(js) != TOK_RPAREN) return js_mkerr(js, ") expected");
	js->consumed = 1;
	return v;
	}
	} else {
	return js_literal(js);
	}
	}

	static jsval_t js_call_dot(struct js *js) {
	jsval_t res = js_group(js);
	jsval_t obj = js_mkundef();
	if (is_err(res)) return res;
	if (vtype(res) == T_CODEREF) {
	if (lookahead(js) == TOK_ARROW) return res;
	res = lookup(js, &js->code[coderefoff(res)], codereflen(res));
	}
	while (next(js) == TOK_LPAREN \|\| next(js) == TOK_DOT \|\| next(js) == TOK_OPTIONAL_CHAIN \|\| next(js) == TOK_LBRACKET) {
	if (js->tok == TOK_DOT \|\| js->tok == TOK_OPTIONAL_CHAIN) {
	uint8_t op = js->tok;
	js->consumed = 1;
	if (vtype(res) != T_PROP) {
	obj = res;
	} else {
	obj = resolveprop(js, res);
	}
	if (op == TOK_OPTIONAL_CHAIN && (vtype(obj) == T_NULL \|\| vtype(obj) == T_UNDEF)) {
	js_group(js);
	res = js_mkundef();
	} else {
	res = do_op(js, op, res, js_group(js));
	}
	} else if (js->tok == TOK_LBRACKET) {
	js->consumed = 1;
	if (vtype(res) != T_PROP) {
	obj = res;
	} else {
	obj = resolveprop(js, res);
	}
	jsval_t idx = js_expr(js);
	if (is_err(idx)) return idx;
	if (next(js) != TOK_RBRACKET) return js_mkerr(js, "] expected");
	js->consumed = 1;
	res = do_op(js, TOK_BRACKET, res, idx);
	} else {
	- jsval_t params = js_call_params(js);
	- if (is_err(params)) return params;
	jsval_t func_this = (vtype(obj) != T_UNDEF) ? obj : js->this_val;
	- jsval_t saved_this = js->this_val;
	- js->caller_this = func_this;
	+ push_this(func_this);
	+ jsval_t params = js_call_params(js);
	+ if (is_err(params)) {
	+ pop_this();
	+ return params;
	+ }
	res = do_op(js, TOK_CALL, res, params);
	- js->this_val = saved_this;
	+ pop_this();
	obj = js_mkundef();
	}
	}
	return res;
	}

	static jsval_t js_postfix(struct js *js) {
	jsval_t res = js_call_dot(js);
	if (is_err(res)) return res;
	next(js);
	if (js->tok == TOK_POSTINC \|\| js->tok == TOK_POSTDEC) {
	js->consumed = 1;
	res = do_op(js, js->tok, res, 0);
	}
	return res;
	}

	static jsval_t js_unary(struct js *js) {
	if (next(js) == TOK_NEW) {
	js->consumed = 1;
	jsval_t obj = mkobj(js, 0);
	jsval_t saved_this = js->this_val;
	js->this_val = obj;
	jsval_t result = js_postfix(js);
	jsval_t constructed_obj = js->this_val;
	js->this_val = saved_this;
	if (vtype(result) == T_OBJ \|\| vtype(result) == T_ARR \|\| vtype(result) == T_PROMISE) return result;
	return constructed_obj;
	} else if (next(js) == TOK_DELETE) {
	js->consumed = 1;
	jsoff_t save_pos = js->pos;
	uint8_t save_tok = js->tok;
	jsval_t operand = js_postfix(js);
	if (js->flags & F_NOEXEC) return js_mktrue();
	if (vtype(operand) != T_PROP) {
	return js_mktrue();
	}
	jsoff_t prop_off = (jsoff_t) vdata(operand);
	if (is_const_prop(js, prop_off)) {
	return js_mkerr(js, "cannot delete constant property");
	}
	jsval_t owner_obj = js_mkundef();
	for (jsoff_t off = 0; off < js->brk;) {
	jsoff_t v = loadoff(js, off);
	jsoff_t cleaned = v & ~(GCMASK \| CONSTMASK);
	jsoff_t n = esize(cleaned);
	if ((cleaned & 3) == T_OBJ) {
	jsoff_t first_prop = cleaned & ~3U;
	if (first_prop == prop_off) {
	owner_obj = mkval(T_OBJ, off);
	break;
	}
	} else if ((cleaned & 3) == T_PROP) {
	jsoff_t next_prop = cleaned & ~3U;
	if (next_prop == prop_off) {
	jsoff_t deleted_next = loadoff(js, prop_off) & ~(GCMASK \| CONSTMASK);
	jsoff_t current = loadoff(js, off);
	saveoff(js, off, (deleted_next & ~3U) \| (current & (GCMASK \| CONSTMASK \| 3U)));
	saveoff(js, prop_off, loadoff(js, prop_off) \| GCMASK);
	js_gc(js);
	return js_mktrue();
	}
	}
	off += n;
	}
	if (vtype(owner_obj) == T_OBJ) {
	jsoff_t obj_off = (jsoff_t) vdata(owner_obj);
	jsoff_t deleted_next = loadoff(js, prop_off) & ~(GCMASK \| CONSTMASK);
	jsoff_t current = loadoff(js, obj_off);
	saveoff(js, obj_off, (deleted_next & ~3U) \| (current & (GCMASK \| CONSTMASK \| 3U)));
	saveoff(js, prop_off, loadoff(js, prop_off) \| GCMASK);
	js_gc(js);
	}
	(void) save_pos;
	(void) save_tok;
	return js_mktrue();
	} else if (next(js) == TOK_NOT \|\| js->tok == TOK_TILDA \|\| js->tok == TOK_TYPEOF \|\|
	js->tok == TOK_VOID \|\| js->tok == TOK_MINUS \|\| js->tok == TOK_PLUS) {
	uint8_t t = js->tok;
	if (t == TOK_MINUS) t = TOK_UMINUS;
	if (t == TOK_PLUS) t = TOK_UPLUS;
	js->consumed = 1;
	return do_op(js, t, js_mkundef(), js_unary(js));
	} else {
	return js_postfix(js);
	}
	}

	static jsval_t js_mul_div_rem(struct js *js) {
	LTR_BINOP(js_unary, (next(js) == TOK_MUL \|\| js->tok == TOK_DIV \|\| js->tok == TOK_REM));
	}

	static jsval_t js_plus_minus(struct js *js) {
	LTR_BINOP(js_mul_div_rem, (next(js) == TOK_PLUS \|\| js->tok == TOK_MINUS));
	}

	static jsval_t js_shifts(struct js *js) {
	LTR_BINOP(js_plus_minus,
	(next(js) == TOK_SHR \|\| next(js) == TOK_SHL \|\|
	next(js) == TOK_ZSHR));
	}

	static jsval_t js_comparison(struct js *js) {
	LTR_BINOP(js_shifts,
	(next(js) == TOK_LT \|\| next(js) == TOK_LE \|\|
	next(js) == TOK_GT \|\| next(js) == TOK_GE \|\|
	next(js) == TOK_INSTANCEOF));
	}

	static jsval_t js_equality(struct js *js) {
	LTR_BINOP(js_comparison, (next(js) == TOK_EQ \|\| next(js) == TOK_NE));
	}

	static jsval_t js_bitwise_and(struct js *js) {
	LTR_BINOP(js_equality, (next(js) == TOK_AND));
	}

	static jsval_t js_bitwise_xor(struct js *js) {
	LTR_BINOP(js_bitwise_and, (next(js) == TOK_XOR));
	}

	static jsval_t js_bitwise_or(struct js *js) {
	LTR_BINOP(js_bitwise_xor, (next(js) == TOK_OR));
	}

	static jsval_t js_logical_and(struct js *js) {
	jsval_t res = js_bitwise_or(js);
	if (is_err(res)) return res;
	uint8_t flags = js->flags;
	while (next(js) == TOK_LAND) {
	js->consumed = 1;
	res = resolveprop(js, res);
	if (!js_truthy(js, res)) js->flags \|= F_NOEXEC;
	if (js->flags & F_NOEXEC) {
	js_logical_and(js);
	} else {
	res = js_logical_and(js);
	}
	}
	js->flags = flags;
	return res;
	}

	static jsval_t js_logical_or(struct js *js) {
	jsval_t res = js_logical_and(js);
	if (is_err(res)) return res;
	uint8_t flags = js->flags;
	while (next(js) == TOK_LOR) {
	js->consumed = 1;
	res = resolveprop(js, res);
	if (js_truthy(js, res)) js->flags \|= F_NOEXEC;
	if (js->flags & F_NOEXEC) {
	js_logical_or(js);
	} else {
	res = js_logical_or(js);
	}
	}
	js->flags = flags;
	return res;
	}

	static jsval_t js_ternary(struct js *js) {
	jsval_t res = js_logical_or(js);
	if (next(js) == TOK_Q) {
	uint8_t flags = js->flags;
	js->consumed = 1;
	if (js_truthy(js, resolveprop(js, res))) {
	res = js_ternary(js);
	js->flags \|= F_NOEXEC;
	EXPECT(TOK_COLON, js->flags = flags);
	js_ternary(js);
	js->flags = flags;
	} else {
	js->flags \|= F_NOEXEC;
	js_ternary(js);
	EXPECT(TOK_COLON, js->flags = flags);
	js->flags = flags;
	res = js_ternary(js);
	}
	}
	return res;
	}

	static jsval_t js_assignment(struct js *js) {
	jsval_t res = js_ternary(js);

	if (!is_err(res) && vtype(res) == T_CODEREF && next(js) == TOK_ARROW) {
	jsoff_t param_start = coderefoff(res);
	jsoff_t param_len = codereflen(res);
	js->consumed = 1;

	char param_buf[256];
	if (param_len + 3 > sizeof(param_buf)) return js_mkerr(js, "param too long");
	param_buf[0] = '(';
	memcpy(param_buf + 1, &js->code[param_start], param_len);
	param_buf[param_len + 1] = ')';
	param_buf[param_len + 2] = '\0';

	uint8_t flags = js->flags;
	bool is_expr = next(js) != TOK_LBRACE;
	jsoff_t body_start = js->pos;
	if (is_expr && js->tok != TOK_EOF) {
	body_start = js->toff;
	}
	jsval_t body_result;

	if (is_expr) {
	js->flags \|= F_NOEXEC;
	body_result = js_assignment(js);
	if (is_err(body_result)) {
	js->flags = flags;
	return body_result;
	}
	} else {
	js->flags \|= F_NOEXEC;
	js->consumed = 1;
	body_result = js_block(js, false);
	if (is_err(body_result)) {
	js->flags = flags;
	return body_result;
	}
	if (next(js) == TOK_RBRACE) js->consumed = 1;
	}

	js->flags = flags;
	jsoff_t body_end = js->pos;

	size_t fn_size = param_len + (body_end - body_start) + 64;
	char fn_str = (char ) malloc(fn_size);
	if (!fn_str) return js_mkerr(js, "oom");

	jsoff_t fn_pos = 0;
	memcpy(fn_str + fn_pos, param_buf, param_len + 2);
	fn_pos += param_len + 2;
	fn_str[fn_pos++] = '{';

	if (is_expr) {
	memcpy(fn_str + fn_pos, "return ", 7);
	fn_pos += 7;
	size_t body_len = body_end - body_start;
	memcpy(fn_str + fn_pos, &js->code[body_start], body_len);
	fn_pos += body_len;
	} else {
	size_t body_len = body_end - body_start - 2;
	memcpy(fn_str + fn_pos, &js->code[body_start + 1], body_len);
	fn_pos += body_len;
	}

	fn_str[fn_pos++] = '}';

	jsval_t str = js_mkstr(js, fn_str, fn_pos);
	free(fn_str);
	if (is_err(str)) return str;

	jsval_t func_obj = mkobj(js, 0);
	if (is_err(func_obj)) return func_obj;

	jsval_t code_key = js_mkstr(js, "__code", 6);
	if (is_err(code_key)) return code_key;

	jsval_t res2 = setprop(js, func_obj, code_key, str);
	if (is_err(res2)) return res2;

	if (!(flags & F_NOEXEC)) {
	jsval_t scope_key = js_mkstr(js, "__scope", 7);
	if (is_err(scope_key)) return scope_key;
	jsval_t res3 = setprop(js, func_obj, scope_key, js->scope);
	if (is_err(res3)) return res3;
	}

	return mkval(T_FUNC, (unsigned long) vdata(func_obj));
	}

	while (!is_err(res) && (next(js) == TOK_ASSIGN \|\| js->tok == TOK_PLUS_ASSIGN \|\|
	js->tok == TOK_MINUS_ASSIGN \|\| js->tok == TOK_MUL_ASSIGN \|\|
	js->tok == TOK_DIV_ASSIGN \|\| js->tok == TOK_REM_ASSIGN \|\|
	js->tok == TOK_SHL_ASSIGN \|\| js->tok == TOK_SHR_ASSIGN \|\|
	js->tok == TOK_ZSHR_ASSIGN \|\| js->tok == TOK_AND_ASSIGN \|\|
	js->tok == TOK_XOR_ASSIGN \|\| js->tok == TOK_OR_ASSIGN)) {
	uint8_t op = js->tok;
	js->consumed = 1;
	jsval_t rhs = js_assignment(js);
	if (is_err(rhs)) return rhs;
	res = do_op(js, op, res, rhs);
	}

	return res;
	}

	static jsval_t js_decl(struct js *js, bool is_const) {
	uint8_t exe = !(js->flags & F_NOEXEC);
	js->consumed = 1;
	for (;;) {
	if (next(js) == TOK_LBRACE) {
	js->consumed = 1;

	typedef struct { jsoff_t name_off; jsoff_t name_len; } PropName;
	PropName props[32];
	int prop_count = 0;

	while (next(js) != TOK_RBRACE && next(js) != TOK_EOF && prop_count < 32) {
	EXPECT(TOK_IDENTIFIER, );
	props[prop_count].name_off = js->toff;
	props[prop_count].name_len = js->tlen;
	prop_count++;
	js->consumed = 1;

	if (next(js) == TOK_COLON) {
	js->consumed = 1;
	EXPECT(TOK_IDENTIFIER, );
	js->consumed = 1;
	}

	if (next(js) == TOK_RBRACE) break;
	EXPECT(TOK_COMMA, );
	}

	EXPECT(TOK_RBRACE, );

	jsval_t v = js_mkundef();
	if (next(js) == TOK_ASSIGN) {
	js->consumed = 1;
	v = js_expr(js);
	if (is_err(v)) return v;
	} else {
	return js_mkerr(js, "destructuring requires assignment");
	}

	if (exe) {
	jsval_t obj = resolveprop(js, v);
	if (vtype(obj) != T_OBJ && vtype(obj) != T_ARR) {
	return js_mkerr(js, "cannot destructure non-object");
	}

	for (int i = 0; i < prop_count; i++) {
	const char *prop_name = &js->code[props[i].name_off];
	jsoff_t prop_len = props[i].name_len;

	if (lkp(js, js->scope, prop_name, prop_len) > 0) {
	return js_mkerr(js, "'%.*s' already declared", (int) prop_len, prop_name);
	}

	jsoff_t prop_off = lkp(js, obj, prop_name, prop_len);
	jsval_t prop_val = js_mkundef();

	if (prop_off > 0) {
	prop_val = resolveprop(js, mkval(T_PROP, prop_off));
	}

	jsval_t x = mkprop(js, js->scope, js_mkstr(js, prop_name, prop_len), prop_val, is_const);
	if (is_err(x)) return x;
	}
	}
	} else {
	EXPECT(TOK_IDENTIFIER, );
	js->consumed = 0;
	jsoff_t noff = js->toff, nlen = js->tlen;
	char name = (char ) &js->code[noff];
	jsval_t v = js_mkundef();
	js->consumed = 1;
	if (next(js) == TOK_ASSIGN) {
	js->consumed = 1;
	v = js_expr(js);
	if (is_err(v)) return v;
	}
	if (exe) {
	if (lkp(js, js->scope, name, nlen) > 0) return js_mkerr(js, "'%.*s' already declared", (int) nlen, name);
	jsval_t x = mkprop(js, js->scope, js_mkstr(js, name, nlen), resolveprop(js, v), is_const);
	if (is_err(x)) return x;
	}
	}

	if (next(js) == TOK_SEMICOLON \|\| next(js) == TOK_EOF) break;
	EXPECT(TOK_COMMA, );
	}
	return js_mkundef();
	}

	static jsval_t js_expr(struct js *js) {
	return js_assignment(js);
	}

	static jsval_t js_let(struct js *js) {
	return js_decl(js, false);
	}

	static jsval_t js_const(struct js *js) {
	return js_decl(js, true);
	}

	static jsval_t js_func_decl(struct js *js) {
	uint8_t exe = !(js->flags & F_NOEXEC);
	js->consumed = 1;
	EXPECT(TOK_IDENTIFIER, );
	js->consumed = 0;
	jsoff_t noff = js->toff, nlen = js->tlen;
	char name = (char ) &js->code[noff];
	js->consumed = 1;
	EXPECT(TOK_LPAREN, );
	jsoff_t pos = js->pos - 1;
	for (bool comma = false; next(js) != TOK_EOF; comma = true) {
	if (!comma && next(js) == TOK_RPAREN) break;
	EXPECT(TOK_IDENTIFIER, );
	if (next(js) == TOK_RPAREN) break;
	EXPECT(TOK_COMMA, );
	}
	EXPECT(TOK_RPAREN, );
	EXPECT(TOK_LBRACE, );
	js->consumed = 0;
	uint8_t flags = js->flags;
	js->flags \|= F_NOEXEC;
	jsval_t res = js_block(js, false);
	if (is_err(res)) {
	js->flags = flags;
	return res;
	}
	js->flags = flags;
	jsval_t str = js_mkstr(js, &js->code[pos], js->pos - pos);
	jsval_t func_obj = mkobj(js, 0);
	if (is_err(func_obj)) return func_obj;
	jsval_t code_key = js_mkstr(js, "__code", 6);
	if (is_err(code_key)) return code_key;
	jsval_t res2 = setprop(js, func_obj, code_key, str);
	if (is_err(res2)) return res2;
	jsval_t name_key = js_mkstr(js, "name", 4);
	if (is_err(name_key)) return name_key;
	jsval_t name_val = js_mkstr(js, name, nlen);
	if (is_err(name_val)) return name_val;
	jsval_t res3 = setprop(js, func_obj, name_key, name_val);
	if (is_err(res3)) return res3;
	if (exe) {
	jsval_t scope_key = js_mkstr(js, "__scope", 7);
	if (is_err(scope_key)) return scope_key;
	jsval_t res4 = setprop(js, func_obj, scope_key, js->scope);
	if (is_err(res4)) return res4;
	}
	jsval_t func = mkval(T_FUNC, (unsigned long) vdata(func_obj));
	if (exe) {
	if (lkp(js, js->scope, name, nlen) > 0)
	return js_mkerr(js, "'%.*s' already declared", (int) nlen, name);
	jsval_t x = mkprop(js, js->scope, js_mkstr(js, name, nlen), func, false);
	if (is_err(x)) return x;
	}

	return js_mkundef();
	}

	static jsval_t js_func_decl_async(struct js *js) {
	uint8_t exe = !(js->flags & F_NOEXEC);
	js->consumed = 1;
	EXPECT(TOK_IDENTIFIER, );
	js->consumed = 0;
	jsoff_t noff = js->toff, nlen = js->tlen;
	char name = (char ) &js->code[noff];
	js->consumed = 1;
	EXPECT(TOK_LPAREN, );
	jsoff_t pos = js->pos - 1;
	for (bool comma = false; next(js) != TOK_EOF; comma = true) {
	if (!comma && next(js) == TOK_RPAREN) break;
	EXPECT(TOK_IDENTIFIER, );
	if (next(js) == TOK_RPAREN) break;
	EXPECT(TOK_COMMA, );
	}
	EXPECT(TOK_RPAREN, );
	EXPECT(TOK_LBRACE, );
	js->consumed = 0;
	uint8_t flags = js->flags;
	js->flags \|= F_NOEXEC;
	jsval_t res = js_block(js, false);
	if (is_err(res)) {
	js->flags = flags;
	return res;
	}
	js->flags = flags;
	jsval_t str = js_mkstr(js, &js->code[pos], js->pos - pos);
	jsval_t func_obj = mkobj(js, 0);
	if (is_err(func_obj)) return func_obj;
	jsval_t code_key = js_mkstr(js, "__code", 6);
	if (is_err(code_key)) return code_key;
	jsval_t res2 = setprop(js, func_obj, code_key, str);
	if (is_err(res2)) return res2;
	jsval_t async_key = js_mkstr(js, "__async", 7);
	if (is_err(async_key)) return async_key;
	jsval_t res_async = setprop(js, func_obj, async_key, js_mktrue());
	if (is_err(res_async)) return res_async;
	jsval_t name_key = js_mkstr(js, "name", 4);
	if (is_err(name_key)) return name_key;
	jsval_t name_val = js_mkstr(js, name, nlen);
	if (is_err(name_val)) return name_val;
	jsval_t res3 = setprop(js, func_obj, name_key, name_val);
	if (is_err(res3)) return res3;
	if (exe) {
	jsval_t scope_key = js_mkstr(js, "__scope", 7);
	if (is_err(scope_key)) return scope_key;
	jsval_t res4 = setprop(js, func_obj, scope_key, js->scope);
	if (is_err(res4)) return res4;
	}
	jsval_t func = mkval(T_FUNC, (unsigned long) vdata(func_obj));
	if (exe) {
	if (lkp(js, js->scope, name, nlen) > 0)
	return js_mkerr(js, "'%.*s' already declared", (int) nlen, name);
	jsval_t x = mkprop(js, js->scope, js_mkstr(js, name, nlen), func, false);
	if (is_err(x)) return x;
	}

	return js_mkundef();
	}

	static jsval_t js_block_or_stmt(struct js *js) {
	if (next(js) == TOK_LBRACE) return js_block(js, !(js->flags & F_NOEXEC));
	jsval_t res = resolveprop(js, js_stmt(js));
	js->consumed = 0;
	return res;
	}

	static jsval_t js_if(struct js *js) {
	js->consumed = 1;
	EXPECT(TOK_LPAREN, );
	jsval_t res = js_mkundef(), cond = resolveprop(js, js_expr(js));
	EXPECT(TOK_RPAREN, );

	bool cond_true = js_truthy(js, cond), exe = !(js->flags & F_NOEXEC);
	if (!cond_true) js->flags \|= F_NOEXEC;
	jsval_t blk = js_block_or_stmt(js);
	if (cond_true) res = blk;
	if (exe && !cond_true) js->flags &= (uint8_t) ~F_NOEXEC;

	if (lookahead(js) == TOK_ELSE) {
	js->consumed = 1;
	next(js);
	js->consumed = 1;
	if (cond_true) js->flags \|= F_NOEXEC;
	blk = js_block_or_stmt(js);
	if (!cond_true) res = blk;
	if (cond_true && exe) js->flags &= (uint8_t) ~F_NOEXEC;
	}

	return res;
	}

	static inline bool expect(struct js js, uint8_t tok, jsval_t res) {
	if (next(js) != tok) {
	*res = js_mkerr(js, "parse error");
	return false;
	} else {
	js->consumed = 1;
	return true;
	}
	}

	static inline bool is_err2(jsval_t v, jsval_t res) {
	bool r = is_err(*v);
	if (r) res = v;
	return r;
	}

	static jsval_t js_for(struct js *js) {
	uint8_t flags = js->flags, exe = !(flags & F_NOEXEC);
	jsval_t v, res = js_mkundef();
	jsoff_t pos1 = 0, pos2 = 0, pos3 = 0, pos4 = 0;
	if (exe) mkscope(js);
	if (!expect(js, TOK_FOR, &res)) goto done;
	if (!expect(js, TOK_LPAREN, &res)) goto done;
	if (next(js) == TOK_SEMICOLON) {
	} else if (next(js) == TOK_LET) {
	v = js_let(js);
	if (is_err2(&v, &res)) goto done;
	} else if (next(js) == TOK_CONST) {
	v = js_const(js);
	if (is_err2(&v, &res)) goto done;
	} else {
	v = js_expr(js);
	if (is_err2(&v, &res)) goto done;
	}
	if (!expect(js, TOK_SEMICOLON, &res)) goto done;
	js->flags \|= F_NOEXEC;
	pos1 = js->pos;
	if (next(js) != TOK_SEMICOLON) {
	v = js_expr(js);
	if (is_err2(&v, &res)) goto done;
	}
	if (!expect(js, TOK_SEMICOLON, &res)) goto done;
	pos2 = js->pos;
	if (next(js) != TOK_RPAREN) {
	v = js_expr(js);
	if (is_err2(&v, &res)) goto done;
	}
	if (!expect(js, TOK_RPAREN, &res)) goto done;
	pos3 = js->pos;
	v = js_block_or_stmt(js);
	if (is_err2(&v, &res)) goto done;
	pos4 = js->pos;
	while (!(flags & F_NOEXEC)) {
	js->flags = flags, js->pos = pos1, js->consumed = 1;
	if (next(js) != TOK_SEMICOLON) {
	v = resolveprop(js, js_expr(js));
	if (is_err2(&v, &res)) goto done;
	if (!js_truthy(js, v)) break;
	}
	js->pos = pos3, js->consumed = 1, js->flags \|= F_LOOP;
	v = js_block_or_stmt(js);
	if (is_err2(&v, &res)) goto done;
	if (js->flags & F_BREAK) break;
	if (js->flags & F_RETURN) {
	res = v;
	break;
	}
	js->flags = flags, js->pos = pos2, js->consumed = 1;
	if (next(js) != TOK_RPAREN) {
	v = js_expr(js);
	if (is_err2(&v, &res)) goto done;
	}
	}
	js->pos = pos4, js->tok = TOK_SEMICOLON, js->consumed = 0;
	done:
	if (exe) delscope(js);
	uint8_t preserve = 0;
	if (js->flags & F_RETURN) {
	preserve = js->flags & (F_RETURN \| F_NOEXEC);
	}
	js->flags = flags \| preserve;
	return res;
	}

	static jsval_t js_break(struct js *js) {
	if (js->flags & F_NOEXEC) {
	} else {
	if (!(js->flags & F_LOOP)) return js_mkerr(js, "not in loop");
	js->flags \|= F_BREAK \| F_NOEXEC;
	}
	js->consumed = 1;
	return js_mkundef();
	}

	static jsval_t js_continue(struct js *js) {
	if (js->flags & F_NOEXEC) {
	} else {
	if (!(js->flags & F_LOOP)) return js_mkerr(js, "not in loop");
	js->flags \|= F_NOEXEC;
	}
	js->consumed = 1;
	return js_mkundef();
	}

	static jsval_t js_return(struct js *js) {
	uint8_t exe = !(js->flags & F_NOEXEC);
	js->consumed = 1;
	if (exe && !(js->flags & F_CALL)) return js_mkerr(js, "not in func");
	jsval_t res = js_mkundef();

	if (next(js) != TOK_SEMICOLON) {
	res = resolveprop(js, js_expr(js));
	}

	if (exe) {
	js->pos = js->clen;
	js->flags \|= F_RETURN \| F_NOEXEC;
	}

	return res;
	}

	static jsval_t js_class_decl(struct js *js) {
	uint8_t exe = !(js->flags & F_NOEXEC);
	js->consumed = 1;
	EXPECT(TOK_IDENTIFIER, );
	js->consumed = 0;

	jsoff_t class_name_off = js->toff, class_name_len = js->tlen;
	char class_name = (char ) &js->code[class_name_off];
	js->consumed = 1;

	jsoff_t super_off = 0, super_len = 0;
	if (next(js) == TOK_IDENTIFIER && js->tlen == 7 &&
	streq(&js->code[js->toff], js->tlen, "extends", 7)) {
	js->consumed = 1;
	EXPECT(TOK_IDENTIFIER, );
	super_off = js->toff;
	super_len = js->tlen;
	js->consumed = 1;
	}

	EXPECT(TOK_LBRACE, );
	jsoff_t class_body_start = js->pos;
	jsoff_t constructor_params_start = 0, constructor_params_end = 0;
	jsoff_t constructor_body_start = 0, constructor_body_end = 0;
	uint8_t save_flags = js->flags;
	js->flags \|= F_NOEXEC;

	- typedef struct { jsoff_t name_off, name_len, fn_start, fn_end; } MethodInfo;
	+ typedef struct { jsoff_t name_off, name_len, fn_start, fn_end; bool is_async; } MethodInfo;
	MethodInfo methods[32];
	int method_count = 0;

	while (next(js) != TOK_RBRACE && next(js) != TOK_EOF && method_count < 32) {
	+ bool is_async_method = false;
	+ if (next(js) == TOK_ASYNC) {
	+ is_async_method = true;
	+ js->consumed = 1;
	+ }
	EXPECT(TOK_IDENTIFIER, js->flags = save_flags);
	jsoff_t method_name_off = js->toff, method_name_len = js->tlen;
	js->consumed = 1;
	EXPECT(TOK_LPAREN, js->flags = save_flags);
	jsoff_t method_params_start = js->pos - 1;
	for (bool comma = false; next(js) != TOK_EOF; comma = true) {
	if (!comma && next(js) == TOK_RPAREN) break;
	EXPECT(TOK_IDENTIFIER, js->flags = save_flags);
	if (next(js) == TOK_RPAREN) break;
	EXPECT(TOK_COMMA, js->flags = save_flags);
	}
	EXPECT(TOK_RPAREN, js->flags = save_flags);
	jsoff_t method_params_end = js->pos;
	EXPECT(TOK_LBRACE, js->flags = save_flags);
	jsoff_t method_body_start = js->pos - 1;
	js->consumed = 0;
	jsval_t blk = js_block(js, false);
	if (is_err(blk)) {
	js->flags = save_flags;
	return blk;
	}
	jsoff_t method_body_end = js->pos;
	if (streq(&js->code[method_name_off], method_name_len, "constructor", 11)) {
	constructor_params_start = method_params_start;
	constructor_params_end = method_params_end;
	constructor_body_start = method_body_start + 1;
	constructor_body_end = method_body_end - 1;
	} else {
	methods[method_count].name_off = method_name_off;
	methods[method_count].name_len = method_name_len;
	methods[method_count].fn_start = method_params_start;
	methods[method_count].fn_end = method_body_end;
	+ methods[method_count].is_async = is_async_method;
	method_count++;
	}
	js->consumed = 1;
	}

	EXPECT(TOK_RBRACE, js->flags = save_flags);
	js->flags = save_flags;
	js->consumed = 0;

	if (exe) {
	jsoff_t wrapper_size = 256;
	if (constructor_body_start > 0) {
	wrapper_size += constructor_body_end - constructor_body_start;
	}

	for (int i = 0; i < method_count; i++) {
	wrapper_size += methods[i].name_len + 20;
	wrapper_size += methods[i].fn_end - methods[i].fn_start;
	}

	char wrapper = (char ) malloc(wrapper_size);
	if (!wrapper) return js_mkerr(js, "oom");
	jsoff_t wp = 0;

	if (constructor_params_start > 0) {
	jsoff_t plen = constructor_params_end - constructor_params_start;
	memcpy(wrapper + wp, &js->code[constructor_params_start], plen);
	wp += plen;
	} else {
	memcpy(wrapper + wp, "()", 2);
	wp += 2;
	}
	wrapper[wp++] = '{';
	if (constructor_body_start > 0) {
	jsoff_t blen = constructor_body_end - constructor_body_start;
	memcpy(wrapper + wp, &js->code[constructor_body_start], blen);
	wp += blen;
	while (wp > 0 && (wrapper[wp - 1] == ' ' \|\| wrapper[wp - 1] == '\t' \|\|
	wrapper[wp - 1] == '\n' \|\| wrapper[wp - 1] == '\r')) {
	wp--;
	}
	if (wp > 0 && wrapper[wp - 1] != ';' && wrapper[wp - 1] != '}') {
	wrapper[wp++] = ';';
	}
	}
	for (int i = 0; i < method_count; i++) {
	if (wp > 0 && wrapper[wp - 1] != ';' && wrapper[wp - 1] != '{') {
	wrapper[wp++] = ';';
	}
	memcpy(wrapper + wp, "this.", 5);
	wp += 5;
	memcpy(wrapper + wp, &js->code[methods[i].name_off], methods[i].name_len);
	wp += methods[i].name_len;
	wrapper[wp++] = '=';
	+ if (methods[i].is_async) {
	+ memcpy(wrapper + wp, "async ", 6);
	+ wp += 6;
	+ }
	memcpy(wrapper + wp, "function", 8);
	wp += 8;
	jsoff_t mlen = methods[i].fn_end - methods[i].fn_start;
	memcpy(wrapper + wp, &js->code[methods[i].fn_start], mlen);
	wp += mlen;
	wrapper[wp++] = ';';
	}

	wrapper[wp++] = '}';
	jsval_t code_str = js_mkstr(js, wrapper, wp);
	free(wrapper);
	if (is_err(code_str)) return code_str;
	jsval_t func_obj = mkobj(js, 0);
	if (is_err(func_obj)) return func_obj;
	jsval_t code_key = js_mkstr(js, "__code", 6);
	if (is_err(code_key)) return code_key;
	jsval_t res2 = setprop(js, func_obj, code_key, code_str);
	if (is_err(res2)) return res2;
	jsval_t scope_key = js_mkstr(js, "__scope", 7);
	if (is_err(scope_key)) return scope_key;
	jsval_t res3 = setprop(js, func_obj, scope_key, js->scope);
	if (is_err(res3)) return res3;
	jsval_t constructor = mkval(T_FUNC, (unsigned long) vdata(func_obj));
	if (lkp(js, js->scope, class_name, class_name_len) > 0) {
	return js_mkerr(js, "'%.*s' already declared", (int) class_name_len, class_name);
	}
	jsval_t x = mkprop(js, js->scope, js_mkstr(js, class_name, class_name_len), constructor, false);
	if (is_err(x)) return x;
	}

	(void) super_off;
	(void) super_len;
	(void) class_body_start;
	return js_mkundef();
	}

	static jsval_t js_stmt(struct js *js) {
	jsval_t res;
	if (js->brk > js->gct) js_gc(js);

	switch (next(js)) {
	case TOK_CASE: case TOK_CATCH:
	case TOK_DEFAULT: case TOK_DO: case TOK_FINALLY:
	case TOK_IN: case TOK_SWITCH:
	case TOK_THROW: case TOK_TRY: case TOK_VAR:
	case TOK_WITH: case TOK_WHILE: case TOK_YIELD:
	res = js_mkerr(js, "'%.*s' not implemented", (int) js->tlen, js->code + js->toff);
	break;
	case TOK_CONTINUE: res = js_continue(js); break;
	case TOK_BREAK: res = js_break(js); break;
	case TOK_LET: res = js_let(js); break;
	case TOK_CONST: res = js_const(js); break;
	case TOK_FUNC: res = js_func_decl(js); break;
	case TOK_ASYNC: js->consumed = 1; if (next(js) == TOK_FUNC) res = js_func_decl_async(js); else return js_mkerr(js, "async must be followed by function"); break;
	case TOK_CLASS: res = js_class_decl(js); break;
	case TOK_IF: res = js_if(js); break;
	case TOK_LBRACE: res = js_block(js, !(js->flags & F_NOEXEC)); break;
	case TOK_FOR: res = js_for(js); break;
	case TOK_RETURN: res = js_return(js); break;
	default: res = resolveprop(js, js_expr(js)); break;
	}

	if (next(js) != TOK_SEMICOLON && next(js) != TOK_EOF && next(js) != TOK_RBRACE) return js_mkerr(js, "; expected");
	js->consumed = 1;
	return res;
	}

	static jsval_t builtin_String(struct js js, jsval_t args, int nargs) {
	if (nargs == 0) return js_mkstr(js, "", 0);
	jsval_t arg = args[0];
	if (vtype(arg) == T_STR) return arg;
	const char *str = js_str(js, arg);
	return js_mkstr(js, str, strlen(str));
	}

	static jsval_t builtin_Number(struct js js, jsval_t args, int nargs) {
	if (nargs == 0) return tov(0.0);
	jsval_t arg = args[0];

	if (vtype(arg) == T_NUM) return arg;
	if (vtype(arg) == T_BOOL) {
	return tov(vdata(arg) ? 1.0 : 0.0);
	} else if (vtype(arg) == T_STR) {
	jsoff_t len;
	jsoff_t off = vstr(js, arg, &len);
	const char str = (char ) &js->mem[off];
	char *end;
	double val = strtod(str, &end);
	return tov(val);
	} else if (vtype(arg) == T_NULL \|\| vtype(arg) == T_UNDEF) {
	return tov(0.0);
	}

	return tov(0.0);
	}

	static jsval_t builtin_Boolean(struct js js, jsval_t args, int nargs) {
	if (nargs == 0) return mkval(T_BOOL, 0);
	return mkval(T_BOOL, js_truthy(js, args[0]) ? 1 : 0);
	}

	static jsval_t builtin_Object(struct js js, jsval_t args, int nargs) {
	if (nargs == 0) return js_mkobj(js);
	jsval_t arg = args[0];
	if (vtype(arg) == T_NULL \|\| vtype(arg) == T_UNDEF) {
	return js_mkobj(js);
	}
	return arg;
	}

	static jsval_t builtin_Function(struct js js, jsval_t args, int nargs) {
	(void) args;
	(void) nargs;
	return js_mkundef();
	}

	static jsval_t builtin_Array(struct js js, jsval_t args, int nargs) {
	jsval_t arr = mkarr(js);

	if (nargs == 1 && vtype(args[0]) == T_NUM) {
	jsoff_t len = (jsoff_t) tod(args[0]);
	jsval_t len_key = js_mkstr(js, "length", 6);
	jsval_t len_val = tov((double) len);
	setprop(js, arr, len_key, len_val);
	} else {
	for (int i = 0; i < nargs; i++) {
	char idxstr[16];
	snprintf(idxstr, sizeof(idxstr), "%d", i);
	jsval_t key = js_mkstr(js, idxstr, strlen(idxstr));
	setprop(js, arr, key, args[i]);
	}
	jsval_t len_key = js_mkstr(js, "length", 6);
	jsval_t len_val = tov((double) nargs);
	setprop(js, arr, len_key, len_val);
	}

	return mkval(T_ARR, vdata(arr));
	}

	static jsval_t builtin_object_keys(struct js js, jsval_t args, int nargs) {
	if (nargs == 0) return mkarr(js);
	jsval_t obj = args[0];

	if (vtype(obj) != T_OBJ && vtype(obj) != T_ARR && vtype(obj) != T_FUNC) return mkarr(js);
	if (vtype(obj) == T_FUNC) obj = mkval(T_OBJ, vdata(obj));

	jsval_t arr = mkarr(js);
	jsoff_t idx = 0;
	jsoff_t next = loadoff(js, (jsoff_t) vdata(obj)) & ~(3U \| CONSTMASK);

	while (next < js->brk && next != 0) {
	jsoff_t koff = loadoff(js, next + (jsoff_t) sizeof(next));
	jsoff_t klen = offtolen(loadoff(js, koff));
	const char key = (char ) &js->mem[koff + sizeof(koff)];
	char idxstr[16];
	snprintf(idxstr, sizeof(idxstr), "%u", (unsigned) idx);
	jsval_t idx_key = js_mkstr(js, idxstr, strlen(idxstr));
	jsval_t key_val = js_mkstr(js, key, klen);
	setprop(js, arr, idx_key, key_val);
	idx++;
	next = loadoff(js, next) & ~(3U \| CONSTMASK);
	}

	jsval_t len_key = js_mkstr(js, "length", 6);
	jsval_t len_val = tov((double) idx);
	setprop(js, arr, len_key, len_val);
	return mkval(T_ARR, vdata(arr));
	}

	static jsval_t builtin_array_push(struct js js, jsval_t args, int nargs) {
	jsval_t arr = js->this_val;
	arr = resolveprop(js, arr);

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "push called on non-array");
	}

	jsoff_t off = lkp(js, arr, "length", 6);
	jsoff_t len = 0;
	if (off != 0) {
	jsval_t len_val = resolveprop(js, mkval(T_PROP, off));
	if (vtype(len_val) == T_NUM) len = (jsoff_t) tod(len_val);
	}

	for (int i = 0; i < nargs; i++) {
	char idxstr[16];
	snprintf(idxstr, sizeof(idxstr), "%u", (unsigned) len);
	jsval_t key = js_mkstr(js, idxstr, strlen(idxstr));
	setprop(js, arr, key, args[i]);
	len++;
	}

	jsval_t len_key = js_mkstr(js, "length", 6);
	jsval_t len_val = tov((double) len);

	setprop(js, arr, len_key, len_val);
	return len_val;
	}

	static jsval_t builtin_array_pop(struct js js, jsval_t args, int nargs) {
	(void) args;
	(void) nargs;
	jsval_t arr = js->this_val;

	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "pop called on non-array");
	}

	jsoff_t off = lkp(js, arr, "length", 6);
	jsoff_t len = 0;

	if (off != 0) {
	jsval_t len_val = resolveprop(js, mkval(T_PROP, off));
	if (vtype(len_val) == T_NUM) len = (jsoff_t) tod(len_val);
	}

	if (len == 0) return js_mkundef();
	len--;
	char idxstr[16];
	snprintf(idxstr, sizeof(idxstr), "%u", (unsigned) len);

	jsoff_t elem_off = lkp(js, arr, idxstr, strlen(idxstr));
	jsval_t result = js_mkundef();
	if (elem_off != 0) {
	result = resolveprop(js, mkval(T_PROP, elem_off));
	}

	jsval_t len_key = js_mkstr(js, "length", 6);
	jsval_t len_val = tov((double) len);
	setprop(js, arr, len_key, len_val);

	return result;
	}

	static jsval_t builtin_array_slice(struct js js, jsval_t args, int nargs) {
	jsval_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "slice called on non-array");
	}

	jsoff_t off = lkp(js, arr, "length", 6);
	jsoff_t len = 0;

	if (off != 0) {
	jsval_t len_val = resolveprop(js, mkval(T_PROP, off));
	if (vtype(len_val) == T_NUM) len = (jsoff_t) tod(len_val);
	}

	jsoff_t start = 0, end = len;
	if (nargs >= 1 && vtype(args[0]) == T_NUM) {
	double d = tod(args[0]);
	if (d < 0) {
	start = (jsoff_t) (d + len < 0 ? 0 : d + len);
	} else {
	start = (jsoff_t) (d > len ? len : d);
	}
	}

	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	double d = tod(args[1]);
	if (d < 0) {
	end = (jsoff_t) (d + len < 0 ? 0 : d + len);
	} else {
	end = (jsoff_t) (d > len ? len : d);
	}
	}

	if (start > end) start = end;
	jsval_t result = mkarr(js);
	if (is_err(result)) return result;
	jsoff_t result_idx = 0;

	for (jsoff_t i = start; i < end; i++) {
	char idxstr[16];
	snprintf(idxstr, sizeof(idxstr), "%u", (unsigned) i);
	jsoff_t elem_off = lkp(js, arr, idxstr, strlen(idxstr));
	if (elem_off != 0) {
	jsval_t elem = resolveprop(js, mkval(T_PROP, elem_off));
	snprintf(idxstr, sizeof(idxstr), "%u", (unsigned) result_idx);
	jsval_t key = js_mkstr(js, idxstr, strlen(idxstr));
	setprop(js, result, key, elem);
	}
	result_idx++;
	}

	jsval_t len_key = js_mkstr(js, "length", 6);
	setprop(js, result, len_key, tov((double) result_idx));
	return mkval(T_ARR, vdata(result));
	}

	static jsval_t builtin_array_join(struct js js, jsval_t args, int nargs) {
	jsval_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "join called on non-array");
	}
	const char *sep = ",";
	jsoff_t sep_len = 1;

	if (nargs >= 1 && vtype(args[0]) == T_STR) {
	sep_len = 0;
	jsoff_t sep_off = vstr(js, args[0], &sep_len);
	sep = (const char *) &js->mem[sep_off];
	}

	jsoff_t off = lkp(js, arr, "length", 6);
	jsoff_t len = 0;

	if (off != 0) {
	jsval_t len_val = resolveprop(js, mkval(T_PROP, off));
	if (vtype(len_val) == T_NUM) len = (jsoff_t) tod(len_val);
	}

	if (len == 0) return js_mkstr(js, "", 0);
	char result[1024] = "";
	size_t result_len = 0;

	for (jsoff_t i = 0; i < len; i++) {
	char idxstr[16];
	snprintf(idxstr, sizeof(idxstr), "%u", (unsigned) i);
	jsoff_t elem_off = lkp(js, arr, idxstr, strlen(idxstr));

	if (i > 0 && result_len + sep_len < sizeof(result)) {
	memcpy(result + result_len, sep, sep_len);
	result_len += sep_len;
	}

	if (elem_off != 0) {
	jsval_t elem = resolveprop(js, mkval(T_PROP, elem_off));
	if (vtype(elem) == T_STR) {
	jsoff_t elem_len, elem_off_str = vstr(js, elem, &elem_len);
	if (result_len + elem_len < sizeof(result)) {
	memcpy(result + result_len, &js->mem[elem_off_str], elem_len);
	result_len += elem_len;
	}
	} else if (vtype(elem) == T_NUM) {
	char numstr[32];
	snprintf(numstr, sizeof(numstr), "%g", tod(elem));
	size_t num_len = strlen(numstr);
	if (result_len + num_len < sizeof(result)) {
	memcpy(result + result_len, numstr, num_len);
	result_len += num_len;
	}
	} else if (vtype(elem) == T_BOOL) {
	const char *boolstr = vdata(elem) ? "true" : "false";
	size_t bool_len = strlen(boolstr);
	if (result_len + bool_len < sizeof(result)) {
	memcpy(result + result_len, boolstr, bool_len);
	result_len += bool_len;
	}
	}
	}
	}
	return js_mkstr(js, result, result_len);
	}

	static jsval_t builtin_array_includes(struct js js, jsval_t args, int nargs) {
	jsval_t arr = js->this_val;
	if (vtype(arr) != T_ARR && vtype(arr) != T_OBJ) {
	return js_mkerr(js, "includes called on non-array");
	}

	if (nargs == 0) return mkval(T_BOOL, 0);
	jsval_t search = args[0];
	jsoff_t off = lkp(js, arr, "length", 6);
	jsoff_t len = 0;

	if (off != 0) {
	jsval_t len_val = resolveprop(js, mkval(T_PROP, off));
	if (vtype(len_val) == T_NUM) len = (jsoff_t) tod(len_val);
	}

	for (jsoff_t i = 0; i < len; i++) {
	char idxstr[16];
	snprintf(idxstr, sizeof(idxstr), "%u", (unsigned) i);
	jsoff_t elem_off = lkp(js, arr, idxstr, strlen(idxstr));
	if (elem_off != 0) {
	jsval_t elem = resolveprop(js, mkval(T_PROP, elem_off));
	if (vtype(elem) == vtype(search)) {
	if (vtype(elem) == T_NUM && tod(elem) == tod(search)) {
	return mkval(T_BOOL, 1);
	} else if (vtype(elem) == T_BOOL && vdata(elem) == vdata(search)) {
	return mkval(T_BOOL, 1);
	} else if (vtype(elem) == T_STR) {
	jsoff_t elem_len, elem_off_str = vstr(js, elem, &elem_len);
	jsoff_t search_len, search_off = vstr(js, search, &search_len);
	if (elem_len == search_len && memcmp(&js->mem[elem_off_str], &js->mem[search_off], elem_len) == 0) {
	return mkval(T_BOOL, 1);
	}
	} else if ((vtype(elem) == T_OBJ \|\| vtype(elem) == T_ARR \|\| vtype(elem) == T_FUNC) && vdata(elem) == vdata(search)) {
	return mkval(T_BOOL, 1);
	}
	}
	}
	}
	return mkval(T_BOOL, 0);
	}

	static jsval_t builtin_string_indexOf(struct js js, jsval_t args, int nargs) {
	jsval_t str = js->this_val;
	if (vtype(str) != T_STR) return js_mkerr(js, "indexOf called on non-string");
	if (nargs == 0) return tov(-1);
	jsval_t search = args[0];

	if (vtype(search) != T_STR) return tov(-1);
	jsoff_t str_len, str_off = vstr(js, str, &str_len);
	jsoff_t search_len, search_off = vstr(js, search, &search_len);
	const char str_ptr = (char ) &js->mem[str_off];
	const char search_ptr = (char ) &js->mem[search_off];

	for (jsoff_t i = 0; i <= str_len - search_len; i++) {
	if (memcmp(str_ptr + i, search_ptr, search_len) == 0) {
	return tov((double) i);
	}
	}

	return tov(-1);
	}

	static jsval_t builtin_string_substring(struct js js, jsval_t args, int nargs) {
	jsval_t str = js->this_val;
	if (vtype(str) != T_STR) return js_mkerr(js, "substring called on non-string");
	jsoff_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char ) &js->mem[str_off];
	jsoff_t start = 0, end = str_len;

	if (nargs >= 1 && vtype(args[0]) == T_NUM) {
	double d = tod(args[0]);
	start = (jsoff_t) (d < 0 ? 0 : (d > str_len ? str_len : d));
	}

	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	double d = tod(args[1]);
	end = (jsoff_t) (d < 0 ? 0 : (d > str_len ? str_len : d));
	}

	if (start > end) {
	jsoff_t tmp = start;
	start = end;
	end = tmp;
	}

	jsoff_t sub_len = end - start;
	return js_mkstr(js, str_ptr + start, sub_len);
	}

	static jsval_t builtin_string_split(struct js js, jsval_t args, int nargs) {
	jsval_t str = js->this_val;
	if (vtype(str) != T_STR) return js_mkerr(js, "split called on non-string");
	jsoff_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char ) &js->mem[str_off];
	jsval_t arr = mkarr(js);

	if (is_err(arr)) return arr;
	if (nargs == 0 \|\| vtype(args[0]) != T_STR) {
	jsval_t key = js_mkstr(js, "0", 1);
	setprop(js, arr, key, str);
	jsval_t len_key = js_mkstr(js, "length", 6);
	setprop(js, arr, len_key, tov(1));
	return mkval(T_ARR, vdata(arr));
	}

	jsval_t sep = args[0];
	jsoff_t sep_len, sep_off = vstr(js, sep, &sep_len);
	const char sep_ptr = (char ) &js->mem[sep_off];
	jsoff_t idx = 0;
	jsoff_t start = 0;

	if (sep_len == 0) {
	for (jsoff_t i = 0; i < str_len; i++) {
	char idxstr[16];
	snprintf(idxstr, sizeof(idxstr), "%u", (unsigned) idx);
	jsval_t key = js_mkstr(js, idxstr, strlen(idxstr));
	jsval_t part = js_mkstr(js, str_ptr + i, 1);
	setprop(js, arr, key, part);
	idx++;
	}
	} else {
	for (jsoff_t i = 0; i <= str_len - sep_len; i++) {
	if (memcmp(str_ptr + i, sep_ptr, sep_len) == 0) {
	char idxstr[16];
	snprintf(idxstr, sizeof(idxstr), "%u", (unsigned) idx);
	jsval_t key = js_mkstr(js, idxstr, strlen(idxstr));
	jsval_t part = js_mkstr(js, str_ptr + start, i - start);
	setprop(js, arr, key, part);
	idx++;
	start = i + sep_len;
	i += sep_len - 1;
	}
	}
	if (start <= str_len) {
	char idxstr[16];
	snprintf(idxstr, sizeof(idxstr), "%u", (unsigned) idx);
	jsval_t key = js_mkstr(js, idxstr, strlen(idxstr));
	jsval_t part = js_mkstr(js, str_ptr + start, str_len - start);
	setprop(js, arr, key, part);
	idx++;
	}
	}

	jsval_t len_key = js_mkstr(js, "length", 6);
	setprop(js, arr, len_key, tov((double) idx));
	return mkval(T_ARR, vdata(arr));
	}

	static jsval_t builtin_string_slice(struct js js, jsval_t args, int nargs) {
	jsval_t str = js->this_val;
	if (vtype(str) != T_STR) return js_mkerr(js, "slice called on non-string");
	jsoff_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char ) &js->mem[str_off];
	jsoff_t start = 0, end = str_len;

	if (nargs >= 1 && vtype(args[0]) == T_NUM) {
	double d = tod(args[0]);
	if (d < 0) {
	start = (jsoff_t) (d + str_len < 0 ? 0 : d + str_len);
	} else {
	start = (jsoff_t) (d > str_len ? str_len : d);
	}
	}
	if (nargs >= 2 && vtype(args[1]) == T_NUM) {
	double d = tod(args[1]);
	if (d < 0) {
	end = (jsoff_t) (d + str_len < 0 ? 0 : d + str_len);
	} else {
	end = (jsoff_t) (d > str_len ? str_len : d);
	}
	}

	if (start > end) start = end;
	jsoff_t sub_len = end - start;
	return js_mkstr(js, str_ptr + start, sub_len);
	}

	static jsval_t builtin_string_includes(struct js js, jsval_t args, int nargs) {
	jsval_t str = js->this_val;
	if (vtype(str) != T_STR) return js_mkerr(js, "includes called on non-string");
	if (nargs == 0) return mkval(T_BOOL, 0);
	jsval_t search = args[0];

	if (vtype(search) != T_STR) return mkval(T_BOOL, 0);
	jsoff_t str_len, str_off = vstr(js, str, &str_len);
	jsoff_t search_len, search_off = vstr(js, search, &search_len);
	const char str_ptr = (char ) &js->mem[str_off];
	const char search_ptr = (char ) &js->mem[search_off];

	if (search_len == 0) return mkval(T_BOOL, 1);
	for (jsoff_t i = 0; i <= str_len - search_len; i++) {
	if (memcmp(str_ptr + i, search_ptr, search_len) == 0) {
	return mkval(T_BOOL, 1);
	}
	}

	return mkval(T_BOOL, 0);
	}

	static jsval_t builtin_string_startsWith(struct js js, jsval_t args, int nargs) {
	jsval_t str = js->this_val;
	if (vtype(str) != T_STR) return js_mkerr(js, "startsWith called on non-string");
	if (nargs == 0) return mkval(T_BOOL, 0);
	jsval_t search = args[0];

	if (vtype(search) != T_STR) return mkval(T_BOOL, 0);
	jsoff_t str_len, str_off = vstr(js, str, &str_len);
	jsoff_t search_len, search_off = vstr(js, search, &search_len);
	const char str_ptr = (char ) &js->mem[str_off];
	const char search_ptr = (char ) &js->mem[search_off];

	if (search_len > str_len) return mkval(T_BOOL, 0);
	if (search_len == 0) return mkval(T_BOOL, 1);

	return mkval(T_BOOL, memcmp(str_ptr, search_ptr, search_len) == 0 ? 1 : 0);
	}

	static jsval_t builtin_string_endsWith(struct js js, jsval_t args, int nargs) {
	jsval_t str = js->this_val;
	if (vtype(str) != T_STR) return js_mkerr(js, "endsWith called on non-string");
	if (nargs == 0) return mkval(T_BOOL, 0);
	jsval_t search = args[0];

	if (vtype(search) != T_STR) return mkval(T_BOOL, 0);
	jsoff_t str_len, str_off = vstr(js, str, &str_len);
	jsoff_t search_len, search_off = vstr(js, search, &search_len);

	const char str_ptr = (char ) &js->mem[str_off];
	const char search_ptr = (char ) &js->mem[search_off];

	if (search_len > str_len) return mkval(T_BOOL, 0);
	if (search_len == 0) return mkval(T_BOOL, 1);

	return mkval(T_BOOL, memcmp(str_ptr + str_len - search_len, search_ptr, search_len) == 0 ? 1 : 0);
	}

	static jsval_t builtin_string_replace(struct js js, jsval_t args, int nargs) {
	jsval_t str = js->this_val;
	if (vtype(str) != T_STR) return js_mkerr(js, "replace called on non-string");
	if (nargs < 2) return str;

	jsval_t search = args[0];
	jsval_t replacement = args[1];

	if (vtype(search) != T_STR \|\| vtype(replacement) != T_STR) return str;
	jsoff_t str_len, str_off = vstr(js, str, &str_len);
	jsoff_t search_len, search_off = vstr(js, search, &search_len);
	jsoff_t repl_len, repl_off = vstr(js, replacement, &repl_len);

	const char str_ptr = (char ) &js->mem[str_off];
	const char search_ptr = (char ) &js->mem[search_off];
	const char repl_ptr = (char ) &js->mem[repl_off];

	if (search_len > str_len) return str;
	jsoff_t found_at = -1;

	for (jsoff_t i = 0; i <= str_len - search_len; i++) {
	if (memcmp(str_ptr + i, search_ptr, search_len) == 0) {
	found_at = i;
	break;
	}
	}

	if (found_at == -1) return str;
	char result[2048];
	jsoff_t result_len = 0;

	if (found_at > 0 && result_len + found_at < sizeof(result)) {
	memcpy(result + result_len, str_ptr, found_at);
	result_len += found_at;
	}

	if (result_len + repl_len < sizeof(result)) {
	memcpy(result + result_len, repl_ptr, repl_len);
	result_len += repl_len;
	}

	jsoff_t after_start = found_at + search_len;
	jsoff_t after_len = str_len - after_start;

	if (after_len > 0 && result_len + after_len < sizeof(result)) {
	memcpy(result + result_len, str_ptr + after_start, after_len);
	result_len += after_len;
	}

	return js_mkstr(js, result, result_len);
	}

	static jsval_t builtin_string_template(struct js js, jsval_t args, int nargs) {
	jsval_t str = js->this_val;
	if (vtype(str) != T_STR) return js_mkerr(js, "template called on non-string");
	if (nargs < 1 \|\| vtype(args[0]) != T_OBJ) return str;

	jsval_t data = args[0];
	jsoff_t str_len, str_off = vstr(js, str, &str_len);
	const char str_ptr = (char ) &js->mem[str_off];

	char result[2048];
	jsoff_t result_len = 0;
	jsoff_t i = 0;

	while (i < str_len && result_len < sizeof(result) - 1) {
	if (i < str_len - 3 && str_ptr[i] == '{' && str_ptr[i + 1] == '{') {
	jsoff_t start = i + 2;
	jsoff_t end = start;
	while (end < str_len - 1 && !(str_ptr[end] == '}' && str_ptr[end + 1] == '}')) {
	end++;
	}
	if (end < str_len - 1 && str_ptr[end] == '}' && str_ptr[end + 1] == '}') {
	jsoff_t key_len = end - start;
	jsoff_t prop_off = lkp(js, data, str_ptr + start, key_len);

	if (prop_off != 0) {
	jsval_t value = resolveprop(js, mkval(T_PROP, prop_off));
	if (vtype(value) == T_STR) {
	jsoff_t val_len, val_off = vstr(js, value, &val_len);
	if (result_len + val_len < sizeof(result)) {
	memcpy(result + result_len, &js->mem[val_off], val_len);
	result_len += val_len;
	}
	} else if (vtype(value) == T_NUM) {
	char numstr[32];
	snprintf(numstr, sizeof(numstr), "%g", tod(value));
	size_t num_len = strlen(numstr);
	if (result_len + num_len < sizeof(result)) {
	memcpy(result + result_len, numstr, num_len);
	result_len += num_len;
	}
	} else if (vtype(value) == T_BOOL) {
	const char *boolstr = vdata(value) ? "true" : "false";
	size_t bool_len = strlen(boolstr);
	if (result_len + bool_len < sizeof(result)) {
	memcpy(result + result_len, boolstr, bool_len);
	result_len += bool_len;
	}
	}
	} else {
	}
	i = end + 2;
	continue;
	}
	}
	result[result_len++] = str_ptr[i++];
	}
	return js_mkstr(js, result, result_len);
	}

	static jsval_t builtin_string_charCodeAt(struct js js, jsval_t args, int nargs) {
	jsval_t str = js->this_val;
	if (vtype(str) != T_STR) return js_mkerr(js, "charCodeAt called on non-string");
	if (nargs < 1 \|\| vtype(args[0]) != T_NUM) return tov(NAN);

	double idx_d = tod(args[0]);
	if (idx_d < 0 \|\| idx_d != (double)(long)idx_d) return tov(NAN);

	jsoff_t idx = (jsoff_t) idx_d;
	jsoff_t str_len = offtolen(loadoff(js, (jsoff_t) vdata(str)));

	if (idx >= str_len) return tov(NAN);

	jsoff_t str_off = (jsoff_t) vdata(str) + sizeof(jsoff_t);
	unsigned char ch = (unsigned char) js->mem[str_off + idx];

	return tov((double) ch);
	}

	static jsval_t builtin_resolve_internal(struct js js, jsval_t args, int nargs);
	static jsval_t builtin_reject_internal(struct js js, jsval_t args, int nargs);
	static void resolve_promise(struct js *js, jsval_t p, jsval_t val);
	static void reject_promise(struct js *js, jsval_t p, jsval_t val);

	static size_t strpromise(struct js js, jsval_t value, char buf, size_t len) {
	jsval_t prom_obj = mkval(T_OBJ, vdata(value));
	jsoff_t state_off = lkp(js, prom_obj, "__state", 7);
	int state = 0;
	if (state_off != 0) {
	jsval_t val = resolveprop(js, mkval(T_PROP, state_off));
	if (vtype(val) == T_NUM) state = (int)tod(val);
	}

	if (state == 0) {
	return (size_t)snprintf(buf, len, "Promise { <pending> }");
	}

	jsoff_t value_off = lkp(js, prom_obj, "__value", 7);
	if (value_off == 0) {
	const char *s = (state == 1) ? "<fulfilled>" : "<rejected>";
	return (size_t)snprintf(buf, len, "Promise { %s }", s);
	}

	jsval_t prom_val = resolveprop(js, mkval(T_PROP, value_off));
	char value_buf[256];
	size_t value_len = tostr(js, prom_val, value_buf, sizeof(value_buf));
	if (value_len >= sizeof(value_buf)) value_len = sizeof(value_buf) - 1;
	value_buf[value_len] = '\0';

	if (state == 1) {
	return (size_t)snprintf(buf, len, "Promise { %s }", value_buf);
	} else {
	return (size_t)snprintf(buf, len, "Promise { <rejected> %s }", value_buf);
	}
	}

	static jsval_t mkpromise(struct js *js) {
	jsval_t obj = mkobj(js, 0);
	if (is_err(obj)) return obj;
	setprop(js, obj, js_mkstr(js, "__state", 7), tov(0.0));
	setprop(js, obj, js_mkstr(js, "__value", 7), js_mkundef());
	setprop(js, obj, js_mkstr(js, "__handlers", 10), mkarr(js));
	return mkval(T_PROMISE, vdata(obj));
	}

	static jsval_t builtin_trigger_handler_wrapper(struct js js, jsval_t args, int nargs);

	static void trigger_handlers(struct js *js, jsval_t p) {
	jsval_t wrapper_obj = mkobj(js, 0);
	setprop(js, wrapper_obj, js_mkstr(js, "__native_func", 13), js_mkfun(builtin_trigger_handler_wrapper));
	setprop(js, wrapper_obj, js_mkstr(js, "promise", 7), p);
	jsval_t wrapper_fn = mkval(T_FUNC, vdata(wrapper_obj));
	queue_microtask(js, wrapper_fn);
	}

	static jsval_t builtin_trigger_handler_wrapper(struct js js, jsval_t args, int nargs) {
	jsval_t me = js->current_func;
	jsval_t p = js_get(js, me, "promise");
	if (vtype(p) != T_PROMISE) return js_mkundef();

	jsval_t p_obj = mkval(T_OBJ, vdata(p));
	jsoff_t state_off = lkp(js, p_obj, "__state", 7);
	int state = (int)tod(resolveprop(js, mkval(T_PROP, state_off)));

	jsoff_t val_off = lkp(js, p_obj, "__value", 7);
	jsval_t val = resolveprop(js, mkval(T_PROP, val_off));

	jsoff_t handlers_off = lkp(js, p_obj, "__handlers", 10);
	jsval_t handlers_arr = resolveprop(js, mkval(T_PROP, handlers_off));

	jsoff_t len_off = lkp(js, handlers_arr, "length", 6);
	int len = (int)tod(resolveprop(js, mkval(T_PROP, len_off)));

	for (int i = 0; i < len; i += 3) {
	char idx1[16], idx2[16], idx3[16];
	snprintf(idx1, sizeof(idx1), "%d", i);
	snprintf(idx2, sizeof(idx2), "%d", i+1);
	snprintf(idx3, sizeof(idx3), "%d", i+2);

	jsval_t onFulfilled = resolveprop(js, js_get(js, handlers_arr, idx1));
	jsval_t onRejected = resolveprop(js, js_get(js, handlers_arr, idx2));
	jsval_t nextPromise = resolveprop(js, js_get(js, handlers_arr, idx3));

	jsval_t handler = (state == 1) ? onFulfilled : onRejected;

	if (vtype(handler) == T_FUNC \|\| vtype(handler) == T_CFUNC) {
	jsval_t res;
	if (vtype(handler) == T_CFUNC) {
	jsval_t (fn)(struct js , jsval_t , int) = (jsval_t()(struct js , jsval_t , int)) vdata(handler);
	res = fn(js, &val, 1);
	} else {
	jsval_t args[] = { val };
	res = js_call(js, handler, args, 1);
	}

	if (is_err(res)) {
	jsval_t err_str = js_mkstr(js, js->errmsg, strlen(js->errmsg));
	reject_promise(js, nextPromise, err_str);
	} else {
	resolve_promise(js, nextPromise, res);
	}
	} else {
	if (state == 1) resolve_promise(js, nextPromise, val);
	else reject_promise(js, nextPromise, val);
	}
	}
	setprop(js, p_obj, js_mkstr(js, "__handlers", 10), mkarr(js));
	return js_mkundef();
	}

	static void resolve_promise(struct js *js, jsval_t p, jsval_t val) {
	jsval_t p_obj = mkval(T_OBJ, vdata(p));
	jsoff_t state_off = lkp(js, p_obj, "__state", 7);
	if (state_off == 0) return;
	jsval_t state_val = resolveprop(js, mkval(T_PROP, state_off));
	if ((int)tod(state_val) != 0) return;

	if (vtype(val) == T_PROMISE) {
	if (vdata(val) == vdata(p)) {
	jsval_t err = js_mkerr(js, "TypeError: Chaining cycle");
	reject_promise(js, p, err);
	return;
	}
	jsval_t res_obj = mkobj(js, 0);
	setprop(js, res_obj, js_mkstr(js, "__native_func", 13), js_mkfun(builtin_resolve_internal));
	setprop(js, res_obj, js_mkstr(js, "promise", 7), p);
	jsval_t res_fn = mkval(T_FUNC, vdata(res_obj));

	jsval_t rej_obj = mkobj(js, 0);
	setprop(js, rej_obj, js_mkstr(js, "__native_func", 13), js_mkfun(builtin_reject_internal));
	setprop(js, rej_obj, js_mkstr(js, "promise", 7), p);
	jsval_t rej_fn = mkval(T_FUNC, vdata(rej_obj));

	jsval_t args[] = { res_fn, rej_fn };
	jsval_t then_prop = js_get(js, val, "then");
	if (vtype(then_prop) == T_FUNC \|\| vtype(then_prop) == T_CFUNC) {
	jsval_t saved_this = js->this_val;
	js->this_val = val;
	js_call(js, then_prop, args, 2);
	js->this_val = saved_this;
	return;
	}
	}

	setprop(js, p_obj, js_mkstr(js, "__state", 7), tov(1.0));
	setprop(js, p_obj, js_mkstr(js, "__value", 7), val);
	trigger_handlers(js, p);
	}

	static void reject_promise(struct js *js, jsval_t p, jsval_t val) {
	jsval_t p_obj = mkval(T_OBJ, vdata(p));
	jsoff_t state_off = lkp(js, p_obj, "__state", 7);
	if (state_off == 0) return;
	jsval_t state_val = resolveprop(js, mkval(T_PROP, state_off));
	if ((int)tod(state_val) != 0) return;

	setprop(js, p_obj, js_mkstr(js, "__state", 7), tov(2.0));
	setprop(js, p_obj, js_mkstr(js, "__value", 7), val);
	trigger_handlers(js, p);
	}

	static jsval_t builtin_resolve_internal(struct js js, jsval_t args, int nargs) {
	jsval_t me = js->current_func;
	jsval_t p = js_get(js, me, "promise");
	if (vtype(p) != T_PROMISE) return js_mkundef();
	resolve_promise(js, p, nargs > 0 ? args[0] : js_mkundef());
	return js_mkundef();
	}

	static jsval_t builtin_reject_internal(struct js js, jsval_t args, int nargs) {
	jsval_t me = js->current_func;
	jsval_t p = js_get(js, me, "promise");
	if (vtype(p) != T_PROMISE) return js_mkundef();
	reject_promise(js, p, nargs > 0 ? args[0] : js_mkundef());
	return js_mkundef();
	}

	static jsval_t builtin_promise_executor_wrapper(struct js js, jsval_t args, int nargs);

	static jsval_t builtin_Promise(struct js js, jsval_t args, int nargs) {
	jsval_t p = mkpromise(js);
	jsval_t res_obj = mkobj(js, 0);
	setprop(js, res_obj, js_mkstr(js, "__native_func", 13), js_mkfun(builtin_resolve_internal));
	setprop(js, res_obj, js_mkstr(js, "promise", 7), p);
	jsval_t res_fn = mkval(T_FUNC, vdata(res_obj));
	jsval_t rej_obj = mkobj(js, 0);
	setprop(js, rej_obj, js_mkstr(js, "__native_func", 13), js_mkfun(builtin_reject_internal));
	setprop(js, rej_obj, js_mkstr(js, "promise", 7), p);
	jsval_t rej_fn = mkval(T_FUNC, vdata(rej_obj));
	if (nargs > 0) {
	jsval_t wrapper_obj = mkobj(js, 0);
	setprop(js, wrapper_obj, js_mkstr(js, "__native_func", 13), js_mkfun(builtin_promise_executor_wrapper));
	setprop(js, wrapper_obj, js_mkstr(js, "executor", 8), args[0]);
	setprop(js, wrapper_obj, js_mkstr(js, "resolve", 7), res_fn);
	setprop(js, wrapper_obj, js_mkstr(js, "reject", 6), rej_fn);
	jsval_t wrapper_fn = mkval(T_FUNC, vdata(wrapper_obj));
	queue_microtask(js, wrapper_fn);
	}
	return p;
	}

	static jsval_t builtin_promise_executor_wrapper(struct js js, jsval_t args, int nargs) {
	jsval_t me = js->current_func;
	jsval_t executor = js_get(js, me, "executor");
	jsval_t res_fn = js_get(js, me, "resolve");
	jsval_t rej_fn = js_get(js, me, "reject");
	jsval_t exec_args[] = { res_fn, rej_fn };
	js_call(js, executor, exec_args, 2);
	return js_mkundef();
	}

	static jsval_t builtin_Promise_resolve(struct js js, jsval_t args, int nargs) {
	jsval_t val = nargs > 0 ? args[0] : js_mkundef();
	if (vtype(val) == T_PROMISE) return val;
	jsval_t p = mkpromise(js);
	resolve_promise(js, p, val);
	return p;
	}

	static jsval_t builtin_Promise_reject(struct js js, jsval_t args, int nargs) {
	jsval_t val = nargs > 0 ? args[0] : js_mkundef();
	jsval_t p = mkpromise(js);
	reject_promise(js, p, val);
	return p;
	}

	static jsval_t builtin_promise_then(struct js js, jsval_t args, int nargs) {
	jsval_t p = js->this_val;
	if (vtype(p) != T_PROMISE) return js_mkerr(js, "not a promise");
	jsval_t nextP = mkpromise(js);
	jsval_t onFulfilled = nargs > 0 ? args[0] : js_mkundef();
	jsval_t onRejected = nargs > 1 ? args[1] : js_mkundef();
	jsval_t p_obj = mkval(T_OBJ, vdata(p));
	jsval_t handlers = resolveprop(js, js_get(js, p_obj, "__handlers"));
	jsval_t push_args[] = { onFulfilled, onRejected, nextP };
	jsval_t saved_this = js->this_val;
	js->this_val = handlers;
	builtin_array_push(js, push_args, 3);
	js->this_val = saved_this;
	jsoff_t state_off = lkp(js, p_obj, "__state", 7);
	int state = (int)tod(resolveprop(js, mkval(T_PROP, state_off)));
	if (state != 0) trigger_handlers(js, p);
	return nextP;
	}

	static jsval_t builtin_promise_catch(struct js js, jsval_t args, int nargs) {
	jsval_t args_then[] = { js_mkundef(), nargs > 0 ? args[0] : js_mkundef() };
	return builtin_promise_then(js, args_then, 2);
	}

	static jsval_t builtin_promise_finally(struct js js, jsval_t args, int nargs) {
	jsval_t fn = nargs > 0 ? args[0] : js_mkundef();
	jsval_t args_then[] = { fn, fn };
	return builtin_promise_then(js, args_then, 2);
	}

	static jsval_t builtin_Promise_try(struct js js, jsval_t args, int nargs) {
	if (nargs == 0) return builtin_Promise_resolve(js, args, 0);
	jsval_t fn = args[0];
	jsval_t res = js_call(js, fn, NULL, 0);
	if (is_err(res)) {
	jsval_t err_str = js_mkstr(js, js->errmsg, strlen(js->errmsg));
	jsval_t rej_args[] = { err_str };
	return builtin_Promise_reject(js, rej_args, 1);
	}
	jsval_t res_args[] = { res };
	return builtin_Promise_resolve(js, res_args, 1);
	}

	static jsval_t do_instanceof(struct js *js, jsval_t l, jsval_t r) {
	uint8_t ltype = vtype(l);
	if (vtype(r) == T_FUNC) {
	jsval_t func_obj = mkval(T_OBJ, vdata(r));
	jsoff_t native_off = lkp(js, func_obj, "__native_func", 13);
	if (native_off != 0) {
	jsval_t native_val = resolveprop(js, mkval(T_PROP, native_off));
	if (vtype(native_val) == T_CFUNC) {
	jsval_t (fn)(struct js , jsval_t , int) = (jsval_t()(struct js , jsval_t , int)) vdata(native_val);
	if (fn == builtin_Promise) {
	return mkval(T_BOOL, ltype == T_PROMISE ? 1 : 0);
	}
	}
	}
	jsoff_t code_off = lkp(js, func_obj, "__code", 6);
	if (code_off != 0) {
	jsval_t code_val = resolveprop(js, mkval(T_PROP, code_off));
	if (vtype(code_val) == T_STR) {
	jsoff_t fnlen, fnoff = vstr(js, code_val, &fnlen);
	const char code_str = (const char ) (&js->mem[fnoff]);
	if (fnlen == 16 && memcmp(code_str, "__builtin_Object", 16) == 0) {
	return mkval(T_BOOL, ltype == T_OBJ ? 1 : 0);
	}
	}
	}
	}
	if (vtype(r) == T_CFUNC) {
	jsval_t (fn)(struct js , jsval_t , int) = (jsval_t()(struct js , jsval_t , int)) vdata(r);
	if (fn == builtin_Object) {
	return mkval(T_BOOL, ltype == T_OBJ ? 1 : 0);
	} else if (fn == builtin_Function) {
	return mkval(T_BOOL, (ltype == T_FUNC \|\| ltype == T_CFUNC) ? 1 : 0);
	} else if (fn == builtin_String) {
	return mkval(T_BOOL, ltype == T_STR ? 1 : 0);
	} else if (fn == builtin_Number) {
	return mkval(T_BOOL, ltype == T_NUM ? 1 : 0);
	} else if (fn == builtin_Boolean) {
	return mkval(T_BOOL, ltype == T_BOOL ? 1 : 0);
	} else if (fn == builtin_Array) {
	return mkval(T_BOOL, ltype == T_ARR ? 1 : 0);
	} else if (fn == builtin_Promise) {
	return mkval(T_BOOL, ltype == T_PROMISE ? 1 : 0);
	}
	}
	return mkval(T_BOOL, 0);
	}

	struct js js_create(void buf, size_t len) {
	struct js *js = NULL;
	if (len < sizeof(*js) + esize(T_OBJ)) return js;
	memset(buf, 0, len);

	js = (struct js *) buf;
	js->mem = (uint8_t *) (js + 1);
	js->size = (jsoff_t) (len - sizeof(*js));
	js->scope = mkobj(js, 0);
	js->size = js->size / 8U * 8U;
	js->lwm = js->size;
	js->gct = js->size / 2;
	js->this_val = js->scope;
	- js->caller_this = js->scope;

	jsval_t glob = js->scope;
	jsval_t obj_func_obj = mkobj(js, 0);
	jsval_t obj_code_key = js_mkstr(js, "__code", 6);
	jsval_t obj_code_val = js_mkstr(js, "__builtin_Object", 16);
	setprop(js, obj_func_obj, obj_code_key, obj_code_val);
	jsval_t obj_keys_key = js_mkstr(js, "keys", 4);
	setprop(js, obj_func_obj, obj_keys_key, js_mkfun(builtin_object_keys));
	jsval_t obj_func = mkval(T_FUNC, vdata(obj_func_obj));

	setprop(js, glob, js_mkstr(js, "Object", 6), obj_func);
	setprop(js, glob, js_mkstr(js, "Function", 8), js_mkfun(builtin_Function));
	setprop(js, glob, js_mkstr(js, "String", 6), js_mkfun(builtin_String));
	setprop(js, glob, js_mkstr(js, "Number", 6), js_mkfun(builtin_Number));
	setprop(js, glob, js_mkstr(js, "Boolean", 7), js_mkfun(builtin_Boolean));
	setprop(js, glob, js_mkstr(js, "Array", 5), js_mkfun(builtin_Array));

	jsval_t p_proto = js_mkobj(js);
	setprop(js, p_proto, js_mkstr(js, "then", 4), js_mkfun(builtin_promise_then));
	setprop(js, p_proto, js_mkstr(js, "catch", 5), js_mkfun(builtin_promise_catch));
	setprop(js, p_proto, js_mkstr(js, "finally", 7), js_mkfun(builtin_promise_finally));

	jsval_t p_ctor_obj = mkobj(js, 0);
	setprop(js, p_ctor_obj, js_mkstr(js, "__native_func", 13), js_mkfun(builtin_Promise));
	setprop(js, p_ctor_obj, js_mkstr(js, "resolve", 7), js_mkfun(builtin_Promise_resolve));
	setprop(js, p_ctor_obj, js_mkstr(js, "reject", 6), js_mkfun(builtin_Promise_reject));
	setprop(js, p_ctor_obj, js_mkstr(js, "try", 3), js_mkfun(builtin_Promise_try));
	setprop(js, p_ctor_obj, js_mkstr(js, "prototype", 9), p_proto);

	setprop(js, glob, js_mkstr(js, "Promise", 7), mkval(T_FUNC, vdata(p_ctor_obj)));

	return js;
	}

	double js_getnum(jsval_t value) { return tod(value); }
	int js_getbool(jsval_t value) { return vdata(value) & 1 ? 1 : 0; }

	void js_setgct(struct js *js, size_t gct) { js->gct = (jsoff_t) gct; }
	void js_setmaxcss(struct js *js, size_t max) { js->maxcss = (jsoff_t) max; }
	void js_set_filename(struct js js, const char filename) { js->filename = filename; }

	jsval_t js_mktrue(void) { return mkval(T_BOOL, 1); }
	jsval_t js_mkfalse(void) { return mkval(T_BOOL, 0); }
	jsval_t js_mkundef(void) { return mkval(T_UNDEF, 0); }
	jsval_t js_mknull(void) { return mkval(T_NULL, 0); }
	jsval_t js_mknum(double value) { return tov(value); }
	jsval_t js_mkobj(struct js *js) { return mkobj(js, 0); }
	jsval_t js_glob(struct js *js) { (void) js; return mkval(T_OBJ, 0); }
	jsval_t js_mkfun(jsval_t (fn)(struct js , jsval_t , int)) { return mkval(T_CFUNC, (size_t) (void ) fn); }
	jsval_t js_getthis(struct js *js) { return js->this_val; }

	void js_set(struct js js, jsval_t obj, const char key, jsval_t val) {
	if (vtype(obj) == T_OBJ) {
	setprop(js, obj, js_mkstr(js, key, strlen(key)), val);
	} else if (vtype(obj) == T_FUNC) {
	jsval_t func_obj = mkval(T_OBJ, vdata(obj));
	setprop(js, func_obj, js_mkstr(js, key, strlen(key)), val);
	}
	}

	jsval_t js_get(struct js js, jsval_t obj, const char key) {
	if (vtype(obj) == T_FUNC) {
	jsval_t func_obj = mkval(T_OBJ, vdata(obj));
	jsoff_t off = lkp(js, func_obj, key, strlen(key));
	return off == 0 ? js_mkundef() : resolveprop(js, mkval(T_PROP, off));
	}

	if (vtype(obj) != T_OBJ) return js_mkundef();
	jsoff_t off = lkp(js, obj, key, strlen(key));
	return off == 0 ? js_mkundef() : resolveprop(js, mkval(T_PROP, off));
	}

	char js_getstr(struct js js, jsval_t value, size_t *len) {
	if (vtype(value) != T_STR) return NULL;
	jsoff_t n, off = vstr(js, value, &n);
	if (len != NULL) *len = n;
	return (char *) &js->mem[off];
	}

	void js_merge_obj(struct js *js, jsval_t dst, jsval_t src) {
	if (vtype(dst) != T_OBJ \|\| vtype(src) != T_OBJ) return;
	jsoff_t next = loadoff(js, (jsoff_t) vdata(src)) & ~(3U \| CONSTMASK);
	while (next < js->brk && next != 0) {
	jsoff_t koff = loadoff(js, next + (jsoff_t) sizeof(next));
	jsval_t val = loadval(js, next + (jsoff_t) (sizeof(next) + sizeof(koff)));
	jsoff_t klen = offtolen(loadoff(js, koff));

	char key = (char ) &js->mem[koff + sizeof(koff)];
	setprop(js, dst, js_mkstr(js, key, klen), val);
	next = loadoff(js, next) & ~(3U \| CONSTMASK);
	}
	}

	int js_type(jsval_t val) {
	switch (vtype(val)) {
	case T_UNDEF: return JS_UNDEF;
	case T_NULL: return JS_NULL;
	case T_BOOL: return vdata(val) == 0 ? JS_FALSE: JS_TRUE;
	case T_STR: return JS_STR;
	case T_NUM: return JS_NUM;
	case T_ERR: return JS_ERR;
	default: return JS_PRIV;
	}
	}

	void js_stats(struct js js, size_t total, size_t lwm, size_t css) {
	if (total) *total = js->size;
	if (lwm) *lwm = js->lwm;
	if (css) *css = js->css;
	}

	bool js_chkargs(jsval_t args, int nargs, const char spec) {
	int i = 0, ok = 1;
	for (; ok && i < nargs && spec[i]; i++) {
	uint8_t t = vtype(args[i]), c = (uint8_t) spec[i];
	ok = (c == 'b' && t == T_BOOL) \|\| (c == 'd' && t == T_NUM) \|\|
	(c == 's' && t == T_STR) \|\| (c == 'j');
	}
	if (spec[i] != '\0' \|\| i != nargs) ok = 0;
	return ok;
	}

	jsval_t js_eval(struct js js, const char buf, size_t len) {
	jsval_t res = js_mkundef();
	if (len == (size_t) ~0U) len = strlen(buf);
	js->consumed = 1;
	js->tok = TOK_ERR;
	js->code = buf;
	js->clen = (jsoff_t) len;
	js->pos = 0;
	js->cstk = &res;
	while (next(js) != TOK_EOF && !is_err(res)) {
	res = js_stmt(js);
	if (js->flags & F_RETURN) break;
	}
	return res;
	}

	jsval_t js_call(struct js js, jsval_t func, jsval_t args, int nargs) {
	if (vtype(func) == T_CFUNC) {
	jsval_t (fn)(struct js , jsval_t , int) = (jsval_t()(struct js , jsval_t , int)) vdata(func);
	return fn(js, args, nargs);
	} else if (vtype(func) == T_FUNC) {
	jsval_t func_obj = mkval(T_OBJ, vdata(func));
	jsoff_t native_off = lkp(js, func_obj, "__native_func", 13);
	if (native_off != 0) {
	jsval_t native_val = resolveprop(js, mkval(T_PROP, native_off));
	if (vtype(native_val) == T_CFUNC) {
	jsval_t saved_func = js->current_func;
	js->current_func = func;
	jsval_t (fn)(struct js , jsval_t , int) = (jsval_t()(struct js , jsval_t , int)) vdata(native_val);
	jsval_t res = fn(js, args, nargs);
	js->current_func = saved_func;
	return res;
	}
	}
	jsoff_t code_off = lkp(js, func_obj, "__code", 6);

	if (code_off == 0) return js_mkerr(js, "function has no code");
	jsval_t code_val = resolveprop(js, mkval(T_PROP, code_off));
	if (vtype(code_val) != T_STR) return js_mkerr(js, "function code not string");
	jsoff_t fnlen, fnoff = vstr(js, code_val, &fnlen);
	const char fn = (const char ) (&js->mem[fnoff]);
	jsoff_t fnpos = 1;

	uint8_t saved_flags = js->flags;
	js->flags = 0;
	mkscope(js);
	js->flags = saved_flags;
	int arg_idx = 0;

	while (fnpos < fnlen) {
	fnpos = skiptonext(fn, fnlen, fnpos);
	if (fnpos < fnlen && fn[fnpos] == ')') break;
	jsoff_t identlen = 0;
	uint8_t tok = parseident(&fn[fnpos], fnlen - fnpos, &identlen);
	if (tok != TOK_IDENTIFIER) break;
	jsval_t v = arg_idx < nargs ? args[arg_idx] : js_mkundef();
	setprop(js, js->scope, js_mkstr(js, &fn[fnpos], identlen), v);
	arg_idx++;
	fnpos = skiptonext(fn, fnlen, fnpos + identlen);
	if (fnpos < fnlen && fn[fnpos] == ',') fnpos++;
	}

	if (fnpos < fnlen && fn[fnpos] == ')') fnpos++;
	fnpos = skiptonext(fn, fnlen, fnpos);

	if (fnpos < fnlen && fn[fnpos] == '{') fnpos++;
	size_t body_len = fnlen - fnpos - 1;
	+
	+ jsval_t saved_this = js->this_val;
	+ js->this_val = js_glob(js);
	+
	js->flags = F_CALL;
	jsval_t res = js_eval(js, &fn[fnpos], body_len);
	-
	if (!is_err(res) && !(js->flags & F_RETURN)) res = js_mkundef();
	+
	+ js->this_val = saved_this;
	delscope(js);

	return res;
	}
	return js_mkerr(js, "not a function");
	}

	#ifdef JS_DUMP
	void js_dump(struct js *js) {
	jsoff_t off = 0, v;
	printf("JS size %u, brk %u, lwm %u, css %u, nogc %u\n", js->size, js->brk, js->lwm, (unsigned) js->css, js->nogc);
	while (off < js->brk) {
	memcpy(&v, &js->mem[off], sizeof(v));
	printf(" %5u: ", off);
	jsoff_t cleaned = v & ~(GCMASK \| CONSTMASK);
	if ((cleaned & 3U) == T_OBJ) {
	printf("OBJ %u %u%s\n", cleaned & ~3U, loadoff(js, (jsoff_t) (off + sizeof(off))), (v & CONSTMASK) ? " [CONST]" : "");
	} else if ((cleaned & 3U) == T_PROP) {
	jsoff_t koff = loadoff(js, (jsoff_t) (off + sizeof(v)));
	jsval_t val = loadval(js, (jsoff_t) (off + sizeof(v) + sizeof(v)));
	printf("PROP next %u, koff %u vtype %d vdata %lu%s\n", cleaned & ~3U, koff, vtype(val), (unsigned long) vdata(val), (v & CONSTMASK) ? " [CONST]" : "");
	} else if ((cleaned & 3) == T_STR) {
	jsoff_t len = offtolen(cleaned);
	printf("STR %u [%.*s]\n", len, (int) len, js->mem + off + sizeof(v));
	} else {
	printf("???\n");
	break;
	}
	off += esize(v & ~(GCMASK \| CONSTMASK));
	}
	}
	#endif
	diff --git a/tests/test_async_class_methods.cjs b/tests/test_async_class_methods.cjs
	new file mode 100644
	index 0000000..32736e3
	--- /dev/null
	+++ b/tests/test_async_class_methods.cjs
	@@ -0,0 +1,66 @@
	+// Test async methods in classes
	+
	+class AsyncTestClass {
	+ constructor() {
	+ this.name = 'AsyncTestClass';
	+ this.value = 42;
	+ }
	+
	+ // Regular method
	+ regularMethod() {
	+ Ant.println('regularMethod: this.name = ' + this.name);
	+ return this.value;
	+ }
	+
	+ // Async method
	+ async asyncMethod() {
	+ Ant.println('asyncMethod: this.name = ' + this.name);
	+ return Promise.resolve(this.value * 2);
	+ }
	+
	+ // Async method with argument
	+ async asyncWithArg(multiplier) {
	+ Ant.println('asyncWithArg: this.name = ' + this.name + ', multiplier = ' + multiplier);
	+ return Promise.resolve(this.value * multiplier);
	+ }
	+
	+ // Async method that calls helper
	+ async asyncWithHelper() {
	+ function helper() {
	+ return 10;
	+ }
	+ Ant.println('asyncWithHelper: this.name = ' + this.name);
	+ const extra = helper();
	+ return Promise.resolve(this.value + extra);
	+ }
	+}
	+
	+const obj = new AsyncTestClass();
	+
	+Ant.println('=== Test 1: Regular method ===');
	+const result1 = obj.regularMethod();
	+Ant.println('Result: ' + result1);
	+
	+Ant.println('\n=== Test 2: Async method ===');
	+const promise2 = obj.asyncMethod();
	+Ant.println('Returned: ' + (typeof promise2));
	+promise2.then((val) => {
	+ Ant.println('Resolved value: ' + val);
	+ Ant.println('Inside .then(), this.name: ' + this.name);
	+});
	+
	+Ant.println('\n=== Test 3: Async method with argument ===');
	+const promise3 = obj.asyncWithArg(5);
	+Ant.println('Returned: ' + (typeof promise3));
	+promise3.then((val) => {
	+ Ant.println('Resolved value: ' + val);
	+});
	+
	+Ant.println('\n=== Test 4: Async method with helper function ===');
	+const promise4 = obj.asyncWithHelper();
	+Ant.println('Returned: ' + (typeof promise4));
	+promise4.then((val) => {
	+ Ant.println('Resolved value: ' + val);
	+});
	+
	+Ant.println('\n=== All tests completed ===');
	diff --git a/tests/test_async_regular_function.cjs b/tests/test_async_regular_function.cjs
	new file mode 100644
	index 0000000..43bc183
	--- /dev/null
	+++ b/tests/test_async_regular_function.cjs
	@@ -0,0 +1,63 @@
	+// Test that 'this' works with regular functions in async callbacks
	+
	+class AsyncRegularFunctionTest {
	+ constructor(name) {
	+ this.name = name;
	+ this.value = 100;
	+ }
	+
	+ testPromiseWithRegularFunction() {
	+ Ant.println('=== testPromiseWithRegularFunction ===');
	+ Ant.println('Before promise: this.name = ' + this.name);
	+
	+ return Promise.resolve(42).then(function(val) {
	+ Ant.println('Inside .then() with function:');
	+ Ant.println(' typeof this: ' + typeof this);
	+ Ant.println(' this.name: ' + this.name);
	+ Ant.println(' this.value: ' + this.value);
	+ return val + 1;
	+ });
	+ }
	+
	+ testPromiseWithArrowFunction() {
	+ Ant.println('\n=== testPromiseWithArrowFunction ===');
	+ Ant.println('Before promise: this.name = ' + this.name);
	+
	+ return Promise.resolve(42).then((val) => {
	+ Ant.println('Inside .then() with arrow:');
	+ Ant.println(' typeof this: ' + typeof this);
	+ Ant.println(' this.name: ' + this.name);
	+ Ant.println(' this.value: ' + this.value);
	+ return val + 1;
	+ });
	+ }
	+
	+ testMethodCallingPromiseWithFunction() {
	+ Ant.println('\n=== testMethodCallingPromiseWithFunction ===');
	+ const self = this;
	+ Ant.println('Before promise: this.name = ' + this.name);
	+
	+ return Promise.resolve(1).then(function() {
	+ Ant.println('In .then() with function:');
	+ Ant.println(' this.name: ' + this.name);
	+ Ant.println(' self.name: ' + self.name);
	+ return self.value;
	+ });
	+ }
	+}
	+
	+const obj = new AsyncRegularFunctionTest('TestObject');
	+
	+obj.testPromiseWithRegularFunction().then(function(result) {
	+ Ant.println('Result 1: ' + result);
	+});
	+
	+obj.testPromiseWithArrowFunction().then((result) => {
	+ Ant.println('Result 2: ' + result);
	+});
	+
	+obj.testMethodCallingPromiseWithFunction().then((result) => {
	+ Ant.println('Result 3: ' + result);
	+});
	+
	+Ant.println('\n=== All tests queued ===');
	diff --git a/tests/test_async_this.cjs b/tests/test_async_this.cjs
	new file mode 100644
	index 0000000..c41f901
	--- /dev/null
	+++ b/tests/test_async_this.cjs
	@@ -0,0 +1,54 @@
	+// Test async/promise handling with 'this' context
	+
	+class AsyncClass {
	+ constructor() {
	+ this.name = 'AsyncClass';
	+ this.value = 100;
	+ }
	+
	+ asyncMethod(arg) {
	+ Ant.println('asyncMethod called:');
	+ Ant.println(' this.name: ' + this.name);
	+ Ant.println(' this.value: ' + this.value);
	+ Ant.println(' arg: ' + arg);
	+ return Promise.resolve(this.value + 10);
	+ }
	+
	+ methodWithPromise() {
	+ Ant.println('methodWithPromise called:');
	+ Ant.println(' this.name: ' + this.name);
	+
	+ return Promise.resolve(this.value).then((v) => {
	+ Ant.println(' Inside .then(), this.name: ' + this.name);
	+ Ant.println(' Inside .then(), this.value: ' + this.value);
	+ return v * 2;
	+ });
	+ }
	+
	+ nestedAsync(helperFunc) {
	+ Ant.println('nestedAsync called:');
	+ Ant.println(' this.name: ' + this.name);
	+ const result = helperFunc();
	+ Ant.println(' After helper call, this.name: ' + this.name);
	+ return result;
	+ }
	+}
	+
	+function helperFunction() {
	+ return 'helper result';
	+}
	+
	+const obj = new AsyncClass();
	+
	+Ant.println('=== Test 1: Async method ===');
	+const p1 = obj.asyncMethod('test');
	+Ant.println('Promise returned: ' + (typeof p1));
	+
	+Ant.println('\n=== Test 2: Method with promise chain ===');
	+const p2 = obj.methodWithPromise();
	+Ant.println('Promise returned: ' + (typeof p2));
	+
	+Ant.println('\n=== Test 3: Nested call with helper ===');
	+obj.nestedAsync(helperFunction);
	+
	+Ant.println('\n=== All tests completed ===');
	diff --git a/tests/test_async_this_binding.cjs b/tests/test_async_this_binding.cjs
	new file mode 100644
	index 0000000..14ba298
	--- /dev/null
	+++ b/tests/test_async_this_binding.cjs
	@@ -0,0 +1,44 @@
	+// Test explicit this binding in async contexts
	+
	+class TestClass {
	+ constructor(name) {
	+ this.name = name;
	+ }
	+
	+ methodThatReturnsPromise() {
	+ Ant.println('methodThatReturnsPromise: this.name = ' + this.name);
	+
	+ // Use regular function (not arrow) in .then()
	+ return Promise.resolve('value').then(function(val) {
	+ // In standard JS, 'this' would be undefined here
	+ // Let's see what Ant does
	+ Ant.println('In .then() regular function:');
	+ Ant.println(' typeof this: ' + typeof this);
	+ Ant.println(' this: ' + this);
	+
	+ // Try to access properties
	+ if (typeof this.name !== 'undefined') {
	+ Ant.println(' this.name: ' + this.name);
	+ } else {
	+ Ant.println(' this.name is undefined');
	+ }
	+
	+ return val;
	+ });
	+ }
	+}
	+
	+const obj1 = new TestClass('Object1');
	+const obj2 = new TestClass('Object2');
	+
	+Ant.println('=== Calling obj1.methodThatReturnsPromise() ===');
	+obj1.methodThatReturnsPromise().then(function(result) {
	+ Ant.println('Final result: ' + result);
	+});
	+
	+Ant.println('\n=== Calling obj2.methodThatReturnsPromise() ===');
	+obj2.methodThatReturnsPromise().then(function(result) {
	+ Ant.println('Final result: ' + result);
	+});
	+
	+Ant.println('\n=== Tests queued ===');
	diff --git a/tests/test_async_this_context.cjs b/tests/test_async_this_context.cjs
	new file mode 100644
	index 0000000..868aeb7
	--- /dev/null
	+++ b/tests/test_async_this_context.cjs
	@@ -0,0 +1,63 @@
	+// Test that 'this' is preserved in async callbacks
	+
	+class AsyncContextTest {
	+ constructor(name) {
	+ this.name = name;
	+ this.value = 100;
	+ }
	+
	+ testPromiseThen() {
	+ Ant.println('=== testPromiseThen ===');
	+ Ant.println('Before promise: this.name = ' + this.name);
	+
	+ return Promise.resolve(42).then((val) => {
	+ Ant.println('Inside .then(): this.name = ' + this.name);
	+ Ant.println('Inside .then(): this.value = ' + this.value);
	+ return this.value + val;
	+ });
	+ }
	+
	+ testNestedPromises() {
	+ Ant.println('\n=== testNestedPromises ===');
	+ Ant.println('Before promise: this.name = ' + this.name);
	+
	+ return Promise.resolve(10).then((val1) => {
	+ Ant.println('First .then(): this.name = ' + this.name);
	+ return Promise.resolve(val1 + this.value).then((val2) => {
	+ Ant.println('Second .then(): this.name = ' + this.name);
	+ return val2 * 2;
	+ });
	+ });
	+ }
	+
	+ testMethodCallingAsync() {
	+ Ant.println('\n=== testMethodCallingAsync ===');
	+ Ant.println('Before: this.name = ' + this.name);
	+
	+ const helper = () => {
	+ Ant.println('Inside helper: this.name = ' + this.name);
	+ return this.value;
	+ };
	+
	+ return Promise.resolve(1).then(() => {
	+ Ant.println('In .then(), calling helper');
	+ return helper();
	+ });
	+ }
	+}
	+
	+const obj = new AsyncContextTest('TestObject');
	+
	+obj.testPromiseThen().then((result) => {
	+ Ant.println('Result 1: ' + result);
	+});
	+
	+obj.testNestedPromises().then((result) => {
	+ Ant.println('Result 2: ' + result);
	+});
	+
	+obj.testMethodCallingAsync().then((result) => {
	+ Ant.println('Result 3: ' + result);
	+});
	+
	+Ant.println('\n=== All tests queued ===');
	diff --git a/tests/test_deep_this.cjs b/tests/test_deep_this.cjs
	new file mode 100644
	index 0000000..b971de1
	--- /dev/null
	+++ b/tests/test_deep_this.cjs
	@@ -0,0 +1,73 @@
	+// Test deeply nested calls with 'this' context
	+
	+class DeepClass {
	+ constructor(name) {
	+ this.name = name;
	+ this.depth = 0;
	+ }
	+
	+ method1(func) {
	+ Ant.println('method1: this.name = ' + this.name + ', depth = ' + this.depth);
	+ this.depth++;
	+ const result = func();
	+ this.depth--;
	+ return result;
	+ }
	+
	+ method2(func) {
	+ Ant.println('method2: this.name = ' + this.name + ', depth = ' + this.depth);
	+ this.depth++;
	+ const result = func();
	+ this.depth--;
	+ return result;
	+ }
	+
	+ method3(func) {
	+ Ant.println('method3: this.name = ' + this.name + ', depth = ' + this.depth);
	+ this.depth++;
	+ const result = func();
	+ this.depth--;
	+ return result;
	+ }
	+
	+ leaf() {
	+ Ant.println('leaf: this.name = ' + this.name + ', depth = ' + this.depth);
	+ return 'done';
	+ }
	+}
	+
	+function helper1() {
	+ return 'helper1';
	+}
	+
	+function helper2() {
	+ return 'helper2';
	+}
	+
	+const obj1 = new DeepClass('obj1');
	+const obj2 = new DeepClass('obj2');
	+
	+Ant.println('=== Test 1: Deeply nested calls on same object ===');
	+obj1.method1(() => {
	+ return obj1.method2(() => {
	+ return obj1.method3(() => {
	+ return obj1.leaf();
	+ });
	+ });
	+});
	+
	+Ant.println('\n=== Test 2: Interleaved calls on different objects ===');
	+obj1.method1(() => {
	+ obj2.method1(() => {
	+ return obj2.leaf();
	+ });
	+ return obj1.method2(() => {
	+ return obj1.leaf();
	+ });
	+});
	+
	+Ant.println('\n=== Test 3: With helper function calls in arguments ===');
	+obj1.method1(() => helper1());
	+obj2.method2(() => helper2());
	+
	+Ant.println('\n=== All deep nesting tests passed ===');
	diff --git a/tests/test_stack_depth.cjs b/tests/test_stack_depth.cjs
	new file mode 100644
	index 0000000..5ed2c52
	--- /dev/null
	+++ b/tests/test_stack_depth.cjs
	@@ -0,0 +1,51 @@
	+// Test that the this stack is properly managed across async boundaries
	+
	+class StackTest {
	+ constructor(name) {
	+ this.name = name;
	+ }
	+
	+ // Regular method that calls another with function arg
	+ methodA(getArg) {
	+ Ant.println('methodA: this.name = ' + this.name);
	+ return this.methodB(getArg());
	+ }
	+
	+ methodB(arg) {
	+ Ant.println('methodB: this.name = ' + this.name + ', arg = ' + arg);
	+ return this.name + ':' + arg;
	+ }
	+
	+ // Method that returns a promise
	+ asyncMethod() {
	+ Ant.println('asyncMethod: this.name = ' + this.name);
	+ return Promise.resolve(this.name);
	+ }
	+}
	+
	+function helperFunc() {
	+ return 'helper';
	+}
	+
	+const obj1 = new StackTest('obj1');
	+const obj2 = new StackTest('obj2');
	+
	+Ant.println('=== Test 1: Synchronous nested calls ===');
	+const result1 = obj1.methodA(() => helperFunc());
	+Ant.println('Result: ' + result1);
	+
	+Ant.println('\n=== Test 2: Async then sync ===');
	+obj1.asyncMethod().then((val) => {
	+ Ant.println('In .then(), val = ' + val);
	+ // Now do a sync call with function arg
	+ const result = obj2.methodA(() => 'fromPromise');
	+ Ant.println('After sync call: ' + result);
	+});
	+
	+Ant.println('\n=== Test 3: Multiple objects interleaved ===');
	+obj1.methodA(() => {
	+ obj2.methodB('nested');
	+ return 'test';
	+});
	+
	+Ant.println('\n=== All tests done ===');

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