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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 2017 Draft (ECMA-262)
The definition of 'TypedArray.prototype.copyWithin' in that specification.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 45.0 34 (34) No support


No support
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support No support No support 34.0 (34) No support No support No support

See also

Document Tags and Contributors

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