TypedArray.prototype.copyWithin() - JavaScript | MDN
Try it
const uint8 = new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8]);
// Insert position, start position, end position
uint8.copyWithin(3, 1, 3);
console.log(uint8);
// Expected output: Uint8Array [1, 2, 3, 2, 3, 6, 7, 8]
Syntax
js
copyWithin(target, start)
copyWithin(target, start, end)
Parameters
target-
Zero-based index at which to copy the sequence to, converted to an integer. This corresponds to where the element at
startwill be copied to, and all elements betweenstartandendare copied to succeeding indices. start-
Zero-based index at which to start copying elements from, converted to an integer.
endOptional-
Zero-based index at which to end copying elements from, converted to an integer.
copyWithin()copies up to but not includingend.
Return value
The modified typed array.
Description
See Array.prototype.copyWithin() for more details. This method is not generic and can only be called on typed array instances.
Examples
Using copyWithin()
js
const buffer = new ArrayBuffer(8);
const uint8 = new Uint8Array(buffer);
uint8.set([1, 2, 3]);
console.log(uint8); // Uint8Array [ 1, 2, 3, 0, 0, 0, 0, 0 ]
uint8.copyWithin(3, 0, 3);
console.log(uint8); // Uint8Array [ 1, 2, 3, 1, 2, 3, 0, 0 ]
Specifications
| Specification |
|---|
| ECMAScript® 2027 Language Specification # sec-%typedarray%.prototype.copywithin |