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

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
copyWithinChrome Full support 45Edge Full support 14Firefox Full support 34IE No support NoOpera Full support 36Safari No support NoWebView Android No support NoChrome Android No support NoFirefox Android Full support 34Opera Android No support NoSafari iOS No support NoSamsung Internet Android No support Nonodejs Full support 4.0.0


Full support  
Full support
No support  
No support

See also