Web/JavaScript/Reference/Global objects/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

Specification
[(ECMA-262)The definition of 'TypedArray.prototype.lastIndexOf' in that specification.]

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`lastIndexOf`	Chrome Full support 45	Edge Full support 14	Firefox Full support 37 Notes' Full support 37 Notes' Notes' Starting with Firefox 47, this method will no longer return `-0`. For example, `new Uint8Array([0]).lastIndexOf(0, -0)` will now always return `+0`.	IE No support No	Opera Full support 32	Safari Full support 10	WebView Android Full support 45	Chrome Android Full support 45	Firefox Android Full support 37 Notes' Full support 37 Notes' Notes' Starting with Firefox 47, this method will no longer return `-0`. For example, `new Uint8Array([0]).lastIndexOf(0, -0)` will now always return `+0`.	Opera Android Full support 32	Safari iOS Full support 10	Samsung Internet Android Full support 5.0	nodejs Full support 4.0.0

Legend

Full support: Full support
No support: No support
See implementation notes.': See implementation notes.