W3cubDocs

/JavaScript

typedArray.lastIndexOf

The lastIndexOf() method returns the last index at which a given element can be found in the typed array, or -1 if it is not present. The typed array is searched backwards, starting at fromIndex. This method has the same algorithm as Array.prototype.lastIndexOf(). TypedArray is one of the typed array types here.

Syntax

typedarray.lastIndexOf(searchElement[, fromIndex = typedarray.length])

Parameters

searchElement
Element to locate in the typed array.
fromIndex
Optional. The index at which to start searching backwards. Defaults to the typed array's length, i.e. the whole typed array will be searched. If the index is greater than or equal to the length of the typed array, the whole typed array will be searched. If negative, it is taken as the offset from the end of the typed array. Note that even when the index is negative, the typed array is still searched from back to front. If the calculated index is less than 0, -1 is returned, i.e. the typed array will not be searched.

Return value

The last index of the element in the array; -1 if not found.

Description

lastIndexOf compares searchElement to elements of the typed array using strict equality (the same method used by the ===, or triple-equals, operator).

Examples

Using lastIndexOf

var uint8 = new Uint8Array([2, 5, 9, 2]);
uint8.lastIndexOf(2);     // 3
uint8.lastIndexOf(7);     // -1
uint8.lastIndexOf(2, 3);  // 3
uint8.lastIndexOf(2, 2);  // 0
uint8.lastIndexOf(2, -2); // 0
uint8.lastIndexOf(2, -1); // 3

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
lastIndexOf 45 14 37
37
Starting with Firefox 47, this method will no longer return -0. For example, new Uint8Array([0]).lastIndexOf(0, -0) will now always return +0.
No 32 10
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
lastIndexOf 45 45 37
37
Starting with Firefox 47, this method will no longer return -0. For example, new Uint8Array([0]).lastIndexOf(0, -0) will now always return +0.
32 10 5.0
Server
Node.js
lastIndexOf 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/lastIndexOf