Run results for: JavaScript Fastest Array Copy

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:150.0) Gecko/20100101 Firefox/150.0

Browser: Firefox 150

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: 3 months ago

Array.slice

33.0M/s

Slice with begin argument

32.9M/s

Slice with begin and end argument

32.8M/s

Array.concat

24.3M/s

While loop

15.1M/s

For loop with declared length

14.7M/s

For loop

14.4M/s

Spread operator

6.4M/s

View exact numbers

Test name	Executions per second
✓ Array.slice	32,993,010 Ops/sec
Slice with begin argument	32,890,174 Ops/sec
Slice with begin and end argument	32,798,278 Ops/sec
Array.concat	24,338,184 Ops/sec
While loop	15,078,051 Ops/sec
For loop with declared length	14,727,930 Ops/sec
For loop	14,429,202 Ops/sec
Spread operator	6,426,543 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);