Core JavaScript 1.5 Reference:Global Objects:String:lastIndexOf
From MDC
Contents |
[edit] 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, NES2.0 |
| ECMA Version: | ECMA-262 |
[edit] Syntax
lastIndexOf(searchValue[, fromIndex])
[edit] Parameters
-
searchValue - A string representing the value to search for.
-
fromIndex - The location within the calling string to start the search from. It can be any integer between 0 and the length of the string. The default value is the length of the string.
[edit] 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")
[edit] Examples
[edit] 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"))