TypedArray.prototype.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.
The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.
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 index0
. end
Optional- Zero-based index before which to end extraction.
slice
extracts up to but not includingend
. - 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.
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 ]
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.
Specifications
Specification |
---|
ECMAScript (ECMA-262) The definition of '%TypedArray%.prototype.slice' in that specification. |
Browser compatibility
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