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typedArray.slice

The slice() method returns a new typed array (with a new underlying buffer), that contains a copy of a portion of the original typed array. This method has the same algorithm as Array.prototype.slice(). TypedArray is one of the typed array types here.

Syntax

typedarray.slice([begin[, end]])

Parameters

begin Optional
Zero-based index at which to begin extraction.
A negative index can be used, indicating an offset from the end of the sequence. slice(-2) extracts the last two elements in the sequence.
If begin is undefined, slice begins from index 0.
end Optional
Zero-based index before which to end extraction. slice extracts up to but not including end.
For example, slice(1,4) extracts the second element through the fourth element (elements indexed 1, 2, and 3).
A negative index can be used, indicating an offset from the end of the sequence. slice(2,-1) extracts the third element through the second-to-last element in the sequence.
If end is omitted, slice extracts through the end of the sequence (typedarray.length).

Return value

A new typed array containing the extracted elements.

Description

The slice method does not alter. It returns a shallow copy of elements from the original typed array.

If a new element is added to either typed array, the other typed array is not affected.

Polyfill

Since there is no global object with the name TypedArray, polyfilling must be done on an "as needed" basis.

if (!Uint8Array.prototype.slice) {
  Object.defineProperty(Uint8Array.prototype, 'slice', {
    value: function (begin, end)
     {
        return new Uint8Array(Array.prototype.slice.call(this, begin, end));
     }
  });
}

If you need to support truly obsolete JavaScript engines that don't support Object.defineProperty, it's best not to polyfill Array.prototype methods at all, as you can't make them non-enumerable.

Examples

Return a portion of an existing typed array

const uint8 = new Uint8Array([1,2,3]);
uint8.slice(1);   // Uint8Array [ 2, 3 ]
uint8.slice(2);   // Uint8Array [ 3 ]
uint8.slice(-2);  // Uint8Array [ 2, 3 ]
uint8.slice(0,1); // Uint8Array [ 1 ]

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
slice 45 14 38 No 32 10
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
slice 45 45 38 32 10 5.0
Server
Node.js
slice 4.0.0

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/slice