Run results for: JavaScript Array Copy

Run details:

User agent: Mozilla/5.0 (Linux; Android 13; SM-S908B) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Mobile Safari/537.36

Browser: Chrome Mobile 111

Operating system: Android

Device Platform: Mobile

Date tested: one year ago

Test name	Executions per second
Array.concat	3603624.5 Ops/sec
Array.slice	3985444.0 Ops/sec
For loop	119594.2 Ops/sec
For loop with declared length	171939.9 Ops/sec
While loop	181492.3 Ops/sec
Spread operator	3753246.5 Ops/sec
Slice with begin argument	3770216.0 Ops/sec
Slice with begin and end argument	2469823.8 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" ];
var shallowCopy = [];

Tests:

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

Run results for: JavaScript Array Copy

Testing the results for the fastest approach of shallow copying an array in JavaScript (concat, slice, for loop, and while loop).

Array.concat

Array.slice

For loop

For loop with declared length

While loop

Spread operator

Slice with begin argument

Slice with begin and end argument