Ajax function

      function createXHR()
          {
            var xhr;
              if (window.ActiveXObject)
               {
                  try
                     {
                       xhr = new ActiveXObject("Microsoft.XMLHTTP");
                     }
                  catch(e)
                        {
                         alert(e.message);
                         xhr = null;
                         }
               }
              else
                 {
                   xhr = new XMLHttpRequest();
                 }

               return xhr;
           }

To implement 🔢

          var xhr = createXHR();
              xhr.onreadystatechange = function()
                {
                  if (xhr.readyState === 4)
                          {
                            alert(xhr.responseText);
                          }
               }
              xhr.open('GET', 'test.txt', true)
           xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
           xhr.send()

           or
          var param = {id:1};
           xhr.send(param)