[Chapter 21] Reference: String.indexOf()
Author: David Flanagan
Date: Fri Aug 29 11:19:58 1997

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| Chapter 21 JavaScript Reference |

# String.indexOf() Method

## Name

String.indexOf() Method---search a string

## Availability

Navigator 2.0, Internet Explorer 3.0

## Synopsis

    string.indexOf(substring)
    string.indexOf(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 first character of the string.

### Returns

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

## Description

`String.indexOf()` searches the string `string` from beginning to end to see if it contains an occurrence of `substring.` The search begins at position `start` within `string,` or at the beginning of `string,` if `start` is not specified. If an occurrence of `substring` is found, then `String.indexOf()` returns the position of the first character of the first occurrence of `substring` within `string.` Character positions within `string` are numbered starting with zero.

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

## Bugs

In Navigator 2.0 and 3.0, if `start` is greater than the length of `string`, then `indexOf()` returns the empty string rather than -1.

## See Also

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

String.fontsize() |  | String.italics()