Run results for: JavaScript Fastest Array Copy

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser: Chrome 131

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

Slice with begin argument

60.0M/s

Array.slice

51.4M/s

Spread operator

44.4M/s

Array.concat

40.8M/s

Slice with begin and end argument

24.0M/s

While loop

2.5M/s

For loop with declared length

2.4M/s

For loop

2.1M/s

View exact numbers

Test name	Executions per second
✓ Slice with begin argument	60,013,976 Ops/sec
Array.slice	51,393,016 Ops/sec
Spread operator	44,394,212 Ops/sec
Array.concat	40,823,952 Ops/sec
Slice with begin and end argument	23,971,174 Ops/sec
While loop	2,503,187 Ops/sec
For loop with declared length	2,446,208 Ops/sec
For loop	2,062,731 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);