Run results for: JavaScript Fastest Array Copy

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36 Edg/129.0.0.0

Browser: Chrome 129

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Slice with begin argument

30.5M/s

Spread operator

29.4M/s

Array.slice

29.3M/s

Array.concat

28.7M/s

Slice with begin and end argument

14.3M/s

While loop

1.1M/s

For loop with declared length

1.0M/s

For loop

563K/s

View exact numbers

Test name	Executions per second
✓ Slice with begin argument	30,503,984 Ops/sec
Spread operator	29,407,558 Ops/sec
Array.slice	29,312,088 Ops/sec
Array.concat	28,733,262 Ops/sec
Slice with begin and end argument	14,306,228 Ops/sec
While loop	1,080,863 Ops/sec
For loop with declared length	1,011,488 Ops/sec
For loop	563,356 Ops/sec

Script Preparation code:

var arrayToCopy = [ "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello", "hello" ];

Tests:

Array.concat
var shallowCopy = arrayToCopy.concat();
Array.slice
var shallowCopy = arrayToCopy.slice();
For loop
var shallowCopy = []; for (let i = 0; i < arrayToCopy.length; ++i) { shallowCopy.push(arrayToCopy[i]); }
For loop with declared length
var shallowCopy = []; var arrayLength = arrayToCopy.length; for (let i = 0; i < arrayLength; ++i) { shallowCopy.push(arrayToCopy[i]); }
While loop
var shallowCopy = []; let i = arrayToCopy.length - 1; while (i--) { shallowCopy.push(arrayToCopy[i]); }
Spread operator
var shallowCopy = [...arrayToCopy];
Slice with begin argument
var shallowCopy = arrayToCopy.slice(0);
Slice with begin and end argument
var shallowCopy = arrayToCopy.slice(0, arrayToCopy.length);