JSFiddle - React, Tailwind, and code Playground

HTML

<input type="button" value="test" />

JavaScript

$('input[type=button]').click( function() {
  function getQueryVariable(url, variable) {
  	 var query = url.substring(1);
     var vars = query.split('&');
     for (var i=0; i<vars.length; i++) {
          var pair = vars[i].split('=');
          if (pair[0] == variable) {
            return pair[1];
          }
     }

     return false;
  }

  var url = 'http://www.example.com/hello.png?w=100&h=100&bg=white';
       
  var w = getQueryVariable(url, 'w');
  var h = getQueryVariable(url, 'h');
  var bg = getQueryVariable(url, 'bg');

  // http://www.example.com/hello.png?w=200&h=200&bg=white
  var params = { 'w':200, 'h':200, 'bg':bg };
  var new_url = 'http://www.example.com/hello.png?' + jQuery.param(params);
  
  alert(new_url);
});