How to add or update query string parameter to current url in Javascript

 In this post, I will let you know how to add or update query string parameter to current URL using Javascript.

• function updateQueryStringParameter(uri, key, value) {  
•       var re = new RegExp("([?&])" + key + "=.*?(&|$)", "i");  
•       var separator = uri.indexOf('?') !== -1 ? "&" : "?";  
•       if (uri.match(re)) {  
•         return uri.replace(re, '$1' + key + "=" + value + '$2');  
•       }  
•       else {  
•         return uri + separator + key + "=" + value;  
•       }  
• }  

In above example, you will need to pass three argument, first will be your current URL and second will be key which you want to add/update and last argument will be the value of key.

using below example how to use and update a herf attribute 

1. $(".user_nav").each(function () {  
2.                var $that = $(this);  
3.                var oldurl = $that.attr('href');  
4.                var nreUrl = updateQueryStringParameter(oldurl, 'testKey', 'testValue');  
5.                $that.attr('href', nreUrl);  
6. });