Run results for: Counting items in an array ... for vs foreach vs for of

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:94.0) Gecko/20100101 Firefox/94.0

Browser: Firefox 94

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Script Preparation code:

var arr = [];
for (var i = 0; i < 1000000; i++) {
    arr[i] = i % 1000
}

Tests:

For
const countObj = {} for (let i = 0; i < arr.length; i++) { const value = arr[i] countObj[value] = (countObj[value] || 0) + 1 }
Foreach
const countObj = {} arr.forEach(value => { countObj[value] = (countObj[value] || 0) + 1 })
for ... of
const countObj = {} for (let value of arr) { countObj[value] = (countObj[value] || 0) + 1 }