The copyWithin() method copies the sequence of array elements within the array to the position starting at target. The copy is taken from the index positions of the second and third arguments start and end. The end argument is optional and defaults to the length of the array. This method has the same algorithm as Array.prototype.copyWithin. TypedArray is one of the typed array types here.


typedarray.copyWithin(target, start[, end = this.length])


Target start index position where to copy the elements to.
Source start index position where to start copying elements from.
end Optional
Optional. Source end index position where to end copying elements from.

Return value

The modified array.


See Array.prototype.copyWithin for more details.

This method replaces the experimental TypedArray.prototype.move().


var buffer = new ArrayBuffer(8);
var uint8 = new Uint8Array(buffer);
console.log(uint8); // Uint8Array [ 1, 2, 3, 0, 0, 0, 0, 0 ]
console.log(uint8); // Uint8Array [ 1, 2, 3, 1, 2, 3, 0, 0 ]


Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'TypedArray.prototype.copyWithin' in that specification.
Standard Initial definition.
ECMAScript Latest Draft (ECMA-262)
The definition of 'TypedArray.prototype.copyWithin' in that specification.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support451434 No36 No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support No No ?34 No No No

See also

Document Tags and Contributors

Contributors to this page: wbamberg, fscholz, eduardoboucas, halfbyte
Last updated by: wbamberg,