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bench_forin_object_keys.js
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bench_forin_object_keys.js
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function nowMs() {
if (typeof performance !== 'undefined' && performance && typeof performance.now === 'function') {
return performance.now();
}
return Date.now();
}
function parseScale() {
if (typeof process === 'undefined' || !process || !process.argv) return 1;
var raw = Number(process.argv[2]);
return Number.isFinite(raw) && raw > 0 ? raw : 1;
}
function percentile(sorted, p) {
if (sorted.length === 0) return 0;
if (sorted.length === 1) return sorted[0];
var pos = (sorted.length - 1) * p;
var base = Math.floor(pos);
var frac = pos - base;
var next = sorted[base + 1];
if (next === undefined) return sorted[base];
return sorted[base] + (next - sorted[base]) * frac;
}
function stableNumericSort(values) {
var out = values.slice();
for (var i = 1; i < out.length; i++) {
var value = out[i];
var j = i - 1;
while (j >= 0 && out[j] > value) {
out[j + 1] = out[j];
j--;
}
out[j + 1] = value;
}
return out;
}
var SCALE = parseScale();
var WARMUP_RUNS = 2;
var SAMPLE_RUNS = 7;
var sink = 0;
function scaledIters(base) {
return Math.max(1, Math.floor(base * SCALE));
}
function bench(label, fn, iters) {
var warmupIters = Math.max(1, Math.min(iters, Math.max(1000, (iters / 4) | 0)));
for (var i = 0; i < WARMUP_RUNS; i++) sink ^= fn(warmupIters) | 0;
var result = 0;
var samples = [];
for (var j = 0; j < SAMPLE_RUNS; j++) {
var t0 = nowMs();
var r = fn(iters);
var dt = nowMs() - t0;
if (j === 0) result = r;
samples.push(dt);
}
var sorted = stableNumericSort(samples);
var min = sorted[0];
var med = percentile(sorted, 0.5);
var p95 = percentile(sorted, 0.95);
var max = sorted[sorted.length - 1];
var opsPerMs = med > 0 ? (iters / med).toFixed(2) : 'inf';
sink ^= result | 0;
console.log(
label +
': median ' + med.toFixed(2) + 'ms (' + opsPerMs + ' ops/ms)' +
', p95 ' + p95.toFixed(2) + 'ms' +
', min ' + min.toFixed(2) + 'ms' +
', max ' + max.toFixed(2) + 'ms' +
' result=' + result
);
}
function makePlainObject() {
return {
alpha: 1,
beta: 2,
gamma: 3,
delta: 4,
epsilon: 5,
zeta: 6,
eta: 7,
theta: 8,
};
}
function makeMixedIndexObject() {
var obj = {
2: true,
0: true,
1: true,
' ': true,
9: true,
D: true,
B: true,
'-1': true,
};
obj.A = true;
obj[3] = true;
'EFGHIJKLMNOPQRSTUVWXYZ'.split('').forEach(function (key) {
obj[key] = true;
});
Object.defineProperty(obj, 'C', { value: true, enumerable: true });
Object.defineProperty(obj, '4', { value: true, enumerable: true });
delete obj[2];
obj[2] = true;
return obj;
}
function makeShadowObject() {
var proto = {};
var names = 'ABCDEFGHIJKLMNOPQRST'.split('');
for (var i = 0; i < names.length; i++) proto[names[i]] = i;
var obj = Object.create(proto);
obj.keepA = 1;
obj.keepB = 2;
obj.keepC = 3;
for (var j = 0; j < names.length; j++) {
Object.defineProperty(obj, names[j], {
value: j,
enumerable: false,
configurable: true,
});
}
return obj;
}
var plainObj = makePlainObject();
var mixedObj = makeMixedIndexObject();
var shadowObj = makeShadowObject();
function consumeKeys(keys) {
var total = keys.length;
for (var i = 0; i < keys.length; i++) total += keys[i].length;
return total;
}
function benchObjectKeysPlain(n) {
var total = 0;
for (var i = 0; i < n; i++) total += consumeKeys(Object.keys(plainObj));
return total;
}
function benchObjectKeysMixed(n) {
var total = 0;
for (var i = 0; i < n; i++) total += consumeKeys(Object.keys(mixedObj));
return total;
}
function benchForInPlain(n) {
var total = 0;
for (var i = 0; i < n; i++) {
for (var key in plainObj) total += key.length;
}
return total;
}
function benchForInMixed(n) {
var total = 0;
for (var i = 0; i < n; i++) {
for (var key in mixedObj) total += key.length;
}
return total;
}
function benchForInShadow(n) {
var total = 0;
for (var i = 0; i < n; i++) {
for (var key in shadowObj) total += key.length;
}
return total;
}
function benchForInFunctionShadow(n) {
var total = 0;
Object.prototype.length = 42;
for (var i = 0; i < n; i++) {
for (var key in Function) total += key.length;
}
delete Object.prototype.length;
return total;
}
console.log('for-in and Object.keys benchmark');
console.log('scale=' + SCALE);
bench('Object.keys plain', benchObjectKeysPlain, scaledIters(200000));
bench('Object.keys mixed-index', benchObjectKeysMixed, scaledIters(100000));
bench('for-in plain', benchForInPlain, scaledIters(100000));
bench('for-in mixed-index', benchForInMixed, scaledIters(50000));
bench('for-in nonenum-shadow', benchForInShadow, scaledIters(50000));
bench('for-in Function shadow', benchForInFunctionShadow, scaledIters(50000));
console.log('sink=' + sink);

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bench_forin_object_keys.js (4 KB)

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