Javascript trim function attached to the String class

A user defined function attached to String class in javascript

/* Javascript trim function attached to the String class*/

<script language = "javascript" type="text/javascript">

/* Javascript trim function attached to the String class*/
String.prototype.trim = function() {
    return this.replace(/^\s+|\s+$/, '');
};

var str = "Actual:" + " Data            ";
alert(str.trim() + "Here");

</script>