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Run results for:
JavaScript Large Array Copy
Testing the results for the fastest approach of shallow copying an array in JavaScript.
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<iframe src="https://measurethat.net/Embed?id=562344" width="100%" height="500px"></iframe>
Run details:
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36
Browser:
Chrome 130
Operating system:
Windows
Device Platform:
Desktop
Date tested:
one year ago
Test name
Executions per second
Array.concat
318.6 Ops/sec
Slice with begin argument
323.7 Ops/sec
Array.from
316.7 Ops/sec
Array.toSpliced
318.6 Ops/sec
Spread operator
309.8 Ops/sec
For loop
3.8 Ops/sec
Script Preparation code:
var arrayToCopy = Array.from({ length: 1000 * 1000 }, _ => "Hello"); var shallowCopy = [];
Tests:
Array.concat
shallowCopy = arrayToCopy.concat();
Slice with begin argument
shallowCopy = arrayToCopy.slice(0);
Array.from
shallowCopy = Array.from(arrayToCopy);
Array.toSpliced
shallowCopy = arrayToCopy.toSpliced();
Spread operator
shallowCopy = [...arrayToCopy];
For loop
for (let i = 0; i < arrayToCopy.length; i++) { shallowCopy.push(arrayToCopy[i]); }