Benchmark: JavaScript Array Copy 2

JavaScript Array Copy 2 (version: 1)

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

Comparing performance of: `Array.concat vs Array.slice vs For loop vs For loop with declared length vs While loop vs Spread operator vs Slice with begin argument vs Slice with begin and end argument vs Array.from`

Created: one year ago by: Guest

Go to the latest result

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);
Array.from
shallowCopy = Array.from(arrayToCopy);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
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
Array.from

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 130 on Android

View result in a separate tab

Array.slice

4.7M/s

Slice with begin argument

4.7M/s

Array.concat

4.6M/s

Spread operator

4.4M/s

Array.from

3.5M/s

Slice with begin and end argument

2.8M/s

While loop

227K/s

For loop with declared length

217K/s

For loop

142K/s

View exact numbers

Test name	Executions per second
✓ Array.slice	4,734,883 Ops/sec
Slice with begin argument	4,698,656 Ops/sec
Array.concat	4,649,054 Ops/sec
Spread operator	4,433,834 Ops/sec
Array.from	3,519,932 Ops/sec
Slice with begin and end argument	2,841,522 Ops/sec
While loop	227,307 Ops/sec
For loop with declared length	216,816 Ops/sec
For loop	141,942 Ops/sec