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

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.1.2 Safari/605.1.15

Browser: Safari 14

Operating system: Mac OS X 10.15.7

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 }