spread.js
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spread.js
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	import { test, testDeep, summary } from './helpers.js';

	console.log('Spread Tests\n');

	const arr1 = [1, 2, 3];
	const arr2 = [...arr1, 4, 5];
	testDeep('spread array', arr2, [1, 2, 3, 4, 5]);

	const arr3 = [0, ...arr1];
	testDeep('spread at start', arr3, [0, 1, 2, 3]);

	const arr4 = [0, ...arr1, 4];
	testDeep('spread in middle', arr4, [0, 1, 2, 3, 4]);

	const copy = [...arr1];
	testDeep('array copy', copy, [1, 2, 3]);
	test('array copy is new ref', copy !== arr1, true);

	const merged = [...[1, 2], ...[3, 4]];
	testDeep('merge arrays', merged, [1, 2, 3, 4]);

	const obj1 = { a: 1, b: 2 };
	const obj2 = { ...obj1, c: 3 };
	test('spread object a', obj2.a, 1);
	test('spread object c', obj2.c, 3);

	const obj3 = { ...obj1, b: 10 };
	test('spread override', obj3.b, 10);

	const objCopy = { ...obj1 };
	test('object copy a', objCopy.a, 1);
	test('object copy is new ref', objCopy !== obj1, true);

	const mergedObj = { ...{ x: 1 }, ...{ y: 2 } };
	test('merge objects x', mergedObj.x, 1);
	test('merge objects y', mergedObj.y, 2);

	function sum(a, b, c) {
	return a + b + c;
	}
	test('spread in call', sum(...[1, 2, 3]), 6);

	const chars = [...'hello'];
	testDeep('spread string', chars, ['h', 'e', 'l', 'l', 'o']);

	summary();