September 19, 2006

Trimming strings with Javascript

Ben Nadel has a nice post on trimming strings with javascript using regular expressions.

Note that the reg exp white space character ‘\s’ is used to match:

  • space
  • tab
  • horizontal tab
  • vertical tab
  • line break

Sample code below:

<script type="text/javascript">

	// Trims the beginning and trailing white space from a string.
	function trim( strText ){
		return( strText.replace(new RegExp("^([s]+)|([s]+)$", "gm"), "") );

	// Trims the beinning white space from a string.
	function leftTrim( strText ){
		return( strText.replace(new RegExp("^[s]+", "gm"), "") );

	// Trims the trailing white space from a string.
	function rightTrim( strText ){
		return( strText.replace(new RegExp("[s]+$", "gm"), "") );


Javascript: trimString.js

Update 25th March 2007:

    myString.replace(/^\s*|\s*$/g, "");

A basic breakdown:

    Regular expressions in javascript are delimited with forward slashes

    Outside the usual square brackets, the **caret** means look only at the beginning of the target string

    **Alternatation**, meaning finding the left hand OR right have values

    Denotes 0 to many white space characters

    Means look only at the end of the target string

    Makes the search **global**; finding all matches, not just the first match

Of course all we’re doing is replacing left and right white space with an empty string (“”).

© Michael Sharman 2017