The lastIndexOf()
method returns the index within the calling String
object of the last occurrence of the specified value, searching backwards from fromIndex
. Returns -1
if the value is not found.
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
str.lastIndexOf(searchValue[, fromIndex])
Parameters
searchValue
- A string representing the value to search for. If
searchValue
is an empty string, thenfromIndex
is returned. fromIndex
Optional- The index of the last character in the string to be considered as the beginning of a match. The default value is
+Infinity
. IffromIndex >= str.length
, the whole string is searched. IffromIndex < 0
, the behavior will be the same as if it would be0
.
Return value
The index of the last occurrence of searchValue
; -1
if not found.
Description
Characters in a string are indexed from left to right. The index of the first character is 0
, and the index of the last character is str.length - 1
.
'canal'.lastIndexOf('a'); // returns 3 'canal'.lastIndexOf('a', 2); // returns 1 'canal'.lastIndexOf('a', 0); // returns -1 'canal'.lastIndexOf('x'); // returns -1 'canal'.lastIndexOf('c', -5); // returns 0 'canal'.lastIndexOf('c', 0); // returns 0 'canal'.lastIndexOf(''); // returns 5 'canal'.lastIndexOf('', 2); // returns 2
Note: 'abab'.lastIndexOf('ab', 2)
will return 2
and not 0
, as fromIndex
limits only the beginning of the match.
Case-sensitivity
The lastIndexOf()
method is case sensitive. For example, the following expression returns -1
:
'Blue Whale, Killer Whale'.lastIndexOf('blue'); // returns -1
Examples
Using indexOf()
and lastIndexOf()
The following example uses indexOf()
and lastIndexOf()
to locate values in the string "Brave new world"
.
let anyString = 'Brave new world'; console.log('The index of the first w from the beginning is ' + anyString.indexOf('w')); // logs 8 console.log('The index of the first w from the end is ' + anyString.lastIndexOf('w')); // logs 10 console.log('The index of "new" from the beginning is ' + anyString.indexOf('new')); // logs 6 console.log('The index of "new" from the end is ' + anyString.lastIndexOf('new')); // logs 6
Specifications
Specification |
---|
ECMAScript (ECMA-262) The definition of 'String.prototype.lastIndexOf' in that specification. |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
lastIndexOf | Chrome Full support 1 | Edge Full support 12 | Firefox Full support 1 | IE Full support 6 | Opera Full support 3 | Safari Full support 1 | WebView Android Full support 1 | Chrome Android Full support 18 | Firefox Android Full support 4 | Opera Android Full support 10.1 | Safari iOS Full support 1 | Samsung Internet Android Full support 1.0 | nodejs Full support 0.1.100 |
Legend
- Full support
- Full support