Add a Trim,ltrim,rtrim method to a String object in JavaScript

Using the prototype property of each object in JavaScript, we can add our own methods and properties to the built-in objects in JavaScript.
Here's how we use this property to add three methods to a String object: Trim,ltrim,rtrim (acting like a function with the same name in VBScript)
String.prototype.Trim = function ()
{
Return This.replace (/(^\s*) | ( \s*$)/g, "");
}
String.prototype.LTrim = function ()
{
Return This.replace (/(^\s*)/g, "");
}
String.prototype.Rtrim = function ()
{
Return This.replace (/(\s*$)/g, "");
}
How, simple, look at one of the examples used:
<script language=javascript>
String.prototype.Trim = function ()
{
Return This.replace (/(^\s*) | ( \s*$)/g, "");
}

var s = "Leading and trailing spaces";

Window.alert (S + "(" + s.length +) ");

s = S.trim ();

Window.alert (S + "(" + s.length +) ");

</script>