ActionScript: The Definitive Guide

Name

String.indexOf( ) Method — find the first occurrence of a substring in a string

Availability

Flash 5

Synopsis

string.indexOf(substring)
string.indexOf(substring, startIndex)

Arguments

substring

A string containing the character or characters to search for.

startIndex

An optional integer position in string at which to start searching for substring. Should be in the range (the first character) to string .length-1 (the last character). Defaults to 0.

Returns

The position of the first occurrence of substring in string (starting at startIndex). Returns -1 if substring is not found at or after startIndex in string.

Description

The indexOf( ) method is used to search for characters in strings or to check whether a string contains a certain substring.

Example

// Check if an email address contains an @ sign
var email = "derekaol.com";
if (email.indexOf("@") == -1) {
  trace ("This isn't a valid email address");
}

// Check if an email address has an @ sign and is from the domain aol.com
var email = "[e-mail]";
var atPos = email.indexOf("@");
if (atPos != -1 && email.indexOf("aol.com") == atPos + 1) {
  gotoAndStop("AOLuserOffer");
}

The following code shows a generic function that checks for a keyword in a string, as you might need when grading a fill-in-the-blank quiz:

// Generic function to search origStr for any occurrence // of searchStr using a case-insensitive comparison function search (origStr, searchStr) { var origStr = origStr.toLowerCase( ); var searchStr = searchStr.toLowerCase( ); return ...