Getting Querystring value using javascript

This article contains code snippet for getting querystring value using javascript. This below javascript function retrieves query string value from url taking querystring name as parameter
Code Snippet

<script>  
 function getParameterByName(name) {  
 url = window.location.href;  
 name = name.replace(/[\[\]]/g, "\\$&");  
 var regex = new RegExp("[?&]" + name + "(=([^&#]*)|&|#|$)"),  
 results = regex.exec(url);  
 if (!results) return null;  
 if (!results[2]) return '';  
 return decodeURIComponent(results[2].replace(/\+/g, " "));  
 }  
 </script>

Calling above function

This below javascript code calls above declared function for displya querystring value

<script>  
 var vl=getParameterByName('id');  
 if(vl){  
 alert(vl)       
 }  
 </script>