variable = getQueryVariable("what you want to extract");//e.g "source"

function getQueryVariable(variable) {
  var query = window.location.search.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];
    }
  } 
}

This function extracts a value from a url. Very useful for tracking codes. For example, you have a url http://your.url/?source=666999, and you need the source number to be placed into a variable. Use the code below.

Query Variable Function

url, query

JavaScript