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
.
str.lastIndexOf(searchValue[, fromIndex])
searchValue
fromIndex
str.length
. If it is negative, it is treated as 0. If fromIndex > str.length
, fromIndex
is treated as str.length
.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
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')); // 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
Created by Mozilla Contributors and licensed under CC-BY-SA 2.5