Run results for: Array of objects loop for vs foreach vs map vs for..of + slice vs for

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36

Browser: Chrome 123

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

foreach

35K/s

for..of

35K/s

map

33K/s

slice + [x, ...y]

25K/s

slice + [x, ...y] v3

25K/s

slice + [x, ...y] v2

25K/s

for

17K/s

for (no slice)

11K/s

for + push

10K/s

View exact numbers

Test name	Executions per second
✓ foreach	35,142 Ops/sec
for..of	35,130 Ops/sec
map	33,305 Ops/sec
slice + [x, ...y]	25,448 Ops/sec
slice + [x, ...y] v3	25,328 Ops/sec
slice + [x, ...y] v2	25,268 Ops/sec
for	17,394 Ops/sec
for (no slice)	11,480 Ops/sec
for + push	10,318 Ops/sec

Script Preparation code:

   var arr = [];
    for (var i = 0; i < 1000; i++) {
      arr[i] = { data: i };
    }
  
    function someFn(i) {
      return i.data * 3 * 8;
    }

Tests:

foreach
arr.forEach(function (item){ someFn(item); })
for
for (var i = 0, len = arr.length; i < len; i++) { someFn(arr[i]); }
map
arr.map(item => someFn(item))
for..of
for (const el of arr) { someFn(el); }
slice + [x, ...y]
let f=someFn(arr[0]); let rest=arr.slice(1).map(el => (someFn(el))); let result = [f, ...rest];
for (no slice)
let result = [someFn(arr[0])]; for (let i=1; i<arr.length; i++) { result[i] = someFn(arr[i]); }
for + push
let result = [someFn(arr[0])]; for (let i=1; i<arr.length; i++) { result.push(someFn(arr[i])); }
slice + [x, ...y] v2
let result = [someFn(arr[0]), ...arr.slice(1).map(el => (someFn(el)))];
slice + [x, ...y] v3
let rest=arr.slice(1).map(el => (someFn(el))); let result = [someFn(arr[0]), ...rest];