lastIndexOf

Summary

The lastIndexOf() method returns the index within the calling String object of the last occurrence of the specified value, or -1 if not found. The calling string is searched backward, starting at fromIndex.

Syntax

str.lastIndexOf(searchValue[, fromIndex])

Parameters

searchValue
A string representing the value to search for.
fromIndex
The location within the calling string to start the search at, indexed from left to right. It can be any integer between 0 and the length of the string. The default value is the length of the string.

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 stringName.length - 1.

"canal".lastIndexOf("a")   // returns 3
"canal".lastIndexOf("a",2) // returns 1
"canal".lastIndexOf("a",0) // returns -1
"canal".lastIndexOf("x")   // returns -1

Case-sensitivity

The lastIndexOf method is case sensitive. For example, the following expression returns -1:

"Blue Whale, Killer Whale".lastIndexOf("blue"); // returns -1

Examples

Example: Using indexOf and lastIndexOf

The following example uses indexOf and lastIndexOf to locate values in the string "Brave new world".

var anyString = "Brave new world";

console.log("The index of the first w from the beginning is " + anyString.indexOf("w"));
// Displays 8
console.log("The index of the first w from the end is " + anyString.lastIndexOf("w")); 
// Displays 10

console.log("The index of 'new' from the beginning is " + anyString.indexOf("new"));   
// Displays 6
console.log("The index of 'new' from the end is " + anyString.lastIndexOf("new"));
// Displays 6

Specifications

Specification Status Comment
ECMAScript 1st Edition. Standard Initial definition.
ECMAScript Language Specification 5.1th Edition (ECMA-262) Standard  
ECMAScript Language Specification 6th Edition (ECMA-262) Draft  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

Document Tags and Contributors

Contributors to this page: Sevenspade
Last updated by: Sevenspade,
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