lastIndexOf

 

Summary

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.

Method of String
Implemented in	JavaScript 1.0
ECMAScript Edition	ECMAScript 1st Edition

Syntax

string.lastIndexOf(searchValue[, fromIndex])

Parameters

searchValue

A string representing the value to search for.

fromIndex

The location within the calling string to start the search from, 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

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"

// Displays 8
document.write("<P>The index of the first w from the beginning is " +
   anyString.indexOf("w"))
// Displays 10
document.write("<P>The index of the first w from the end is " +
   anyString.lastIndexOf("w"))
// Displays 6
document.write("<P>The index of 'new' from the beginning is " +
   anyString.indexOf("new"))
// Displays 6
document.write("<P>The index of 'new' from the end is " +
   anyString.lastIndexOf("new"))

See Also

charAt, indexOf, split