Actionscript Cookbook

9.12. Trimming Whitespace

Problem

You want to trim the whitespace from the beginning and end of a string.

Solution

Write a custom trim( ) method that splits the string into an array of characters, removes the whitespace from the beginning and end, and then returns the character array as a string using join( ).

Discussion

Extra whitespace at the beginning and end of a string is a common enough annoyance that you should have a way of dealing with it. ActionScript does not provide a native trim( ) method, so you have to write your own.

The custom trim( ) method presented here:

1. Splits the string into an array or characters

2. Removes whitespace elements at the beginning of the array until it finds an element that is not a whitespace character (tab, form feed, carriage return, newline, or space)

3. Removes whitespace elements at the end of the array

4. Uses join( ) to form the array characters into a single string and returns that value

Here is our custom String.trim( ) function. You can add it to a String.as file for easy inclusion in other projects.

String.prototype.trim = function (  ) {

  // Split the string into an array of characters.
  var chars = this.split("");

  // Remove any whitespace elements from the beginning of the array using splice(  ).
  // Use a break statement to exit the loop when you reach a non-whitespace character // to prevent it from removing whitespace in the middle of the string. for (var i = 0; i < chars.length; i++) { if (chars[i] == "\r" || chars[i] == "\n" || chars[i] == "\f" || ...