Run results for: JavaScript Fastest Array Copy

Run details:

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Mobile Safari/537.36

Browser: Chrome Mobile 134

Operating system: Android

Device Platform: Mobile

Date tested: one year ago

Test name	Executions per second
Array.concat	43446608.0 Ops/sec
Array.slice	58199104.0 Ops/sec
For loop	2263549.2 Ops/sec
For loop with declared length	2529748.5 Ops/sec
While loop	2601110.0 Ops/sec
Spread operator	41771828.0 Ops/sec
Slice with begin argument	57034632.0 Ops/sec
Slice with begin and end argument	22680618.0 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);

Run results for: JavaScript Fastest Array Copy

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

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