[Chapter 21] Reference: String.lastIndexOf()
Author: David Flanagan
Date: Fri Aug 29 11:20:01 1997

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| Chapter 21 JavaScript Reference |

# String.lastIndexOf() Method

## Name

String.lastIndexOf() Method---search a string backwards

## Availability

Navigator 2.0, Internet Explorer 3.0

## Synopsis

    string.lastIndexOf(substring)
    string.lastIndexOf(substring, start)

### Arguments

`substring`

  The substring that is to be searched for within `string.`

`start`

  An optional integer argument that specifies the position within `string` at which the search is to start. Legal values are 0 (the position of the first character in the string) to `string``.length`-1 (the position of the last character in the string). If this argument is omitted, then the search begins at the last character of the string.

### Returns

The position of the last occurrence of `substring` within `string` that appears before the `start` position, if any, or -1 if no such occurrence is found within `string.`

## Description

`String.lastIndexOf()` searches the string from end to beginning to see if it contains an occurrence of `substring.` The search begins at position `start` within `string,` or at the end of `string` if `start` is not specified. If an occurrence of `substring` is found, then `String.lastIndexOf()` returns the position of the first character of that occurrence. Since this method searches from end to beginning of the string, the first occurrence found will be the last one in the string that occurs before the `start` position.

If no occurrence of `substring` is found, then `String.lastIndexOf()` returns -1.

Note that although `String.lastIndexOf()` searches `string` from end to beginning, it still numbers character positions within `string` from the beginning. The first character of the string has position 0, and the last has position `string``.length`-1.

## See Also

"String", "String.charAt()", "String.indexOf()", "String.substring()"

String.italics() |  | String.length