JavaScript - for, for-each and forEach performance test

In this article, I would like to show results from simple performance tests for different types of for loop made on int array in JavaScript (V8 in Google Chrome v92).

Tests show what loop type is faster in different cases.

Below test conclusions:

• for loop is fastest in most cases,
• in some cases forEach was faster.
• for some arrays sizes for loop is always faster, and for other forEach method.

Used JavaScript Engine: V8 in Google Chrome v92

Used OS: Windows 10 x64

Used PC:

• Ryzen 9 5900x
• DRR 4 (2x 32GB)
• Samsung SSD M.2 970 EVO (1TB)
• GeForce GTX 970 (4GB RAM)

Total times needed to iterate over the array:

Used source code:

const test = (description, action) => {
	console.time(description);
  	action();
	console.timeEnd(description);
};


// Usage example:

const array = Array(1000); // change it to desired size

for (let i = 0; i < array.length; i++) {
	array[i] = i;
}

test('for loop', () => {
	let sum = 0;
	for (let i = 0; i < array.length; i++) {
		sum += array[i];
	}
	console.log(`sum: ${sum}`);
});

test('for-each loop', () => {
	let sum = 0;
    for (const value of array) {
		sum += value;
	}
	console.log(`sum: ${sum}`);
});

test('forEach() method', () => {
    let sum = 0;
    array.forEach(value => sum += value);
	console.log(`sum: ${sum}`);
});