Run results for: Performance of JS .foreach, for, for...of

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0

Browser: Firefox 128

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

For

38/s

For...Of

33/s

ForEach

32/s

View exact numbers

Test name	Executions per second
✓ For	38 Ops/sec
For...Of	33 Ops/sec
ForEach	32 Ops/sec

Script Preparation code:

function generateTestArray() {
    const result = [];
    for (let i = 0; i < 1000000; ++i) {
        result.push({
            a: i,
            b: i / 2,
            x: 0,
            y: 0,
        });
    }
    return result;
}

Tests:

For
const array = generateTestArray(); for (let i = 0; i < array.length; i++) { array[0].x = array[0].a + array[0].b; array[0].y = array[0].a + array[0].b * 2; }
For...Of
const array = generateTestArray(); for (const a of array) { a.x = a.a + a.b; a.y = a.a + a.b * 2; }
ForEach
const array = generateTestArray(); array.forEach(a => { a.x = a.a + a.b; a.y = a.a + a.b * 2; });

Run results for: Performance of JS .foreach, for, for...of

Comparing performance between different loops in javascript

For

For...Of

ForEach