GET Superglobal in Javascript

GET Superglobal in Javascript

var getParam = (function() {
  var query = location.search.substr(1);
  var params = {};
  if(query) {
    query.split("&").forEach(function(part) {
      var item = part.split("=");
      params[item[0]] = decodeURIComponent(item[1]);
    });
  }
  return function(paramName) {
    if(undefined != paramName) {
      return typeof params[paramName] !== 'undefined' ? params[paramName] : '';
    } else {
      return params;
    }
  }
})();




// https://testdomain.com/page1/?utm_source=yahoo.com&utm_medium=b1_publisher
console.log(getParam()); //{utm_source: "yahoo.com", utm_medium: "b1_publisher"}
console.log(getParam('utm_source')); // "yahoo.com"