AJAX-REQUEST.JS

One of the best innovations brought to web programming, is the ability to request server data from a page, without having to refresh it completely. This is a generic template one can use to make AJAX calls from a web page. One simplification I have implemented in many of my projects, is that instead of XML, my scripts generate JavaScript. It saves me the trouble of having to parse the AJAX response text.

function getXMLObject()
{
         var xmlHttp = null;
         try
         {
           xmlHttp = new XMLHttpRequest();
         }
         catch(e)
         {
              try
              {
                  xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
              }
              catch(e)
              {
                   try
                   {
                       xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
                   }
                   catch(e)
                   {
                         xmlHttp = null;
                   }
              }
         }

         return(xmlHttp);
}

var ajax = getXMLObject();

function ajax_request(url, parameters)
{
         ajax.onreadystatechange = ajax_state;
         
         ajax.open('POST', url, true);

         ajax.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
	 ajax.setRequestHeader('Content-length', parameters.length);
	 ajax.setRequestHeader('Connection', 'close');

         ajax.send(parameters);
}

function ajax_state()
{
         if(ajax.readyState == 4)
         {            
            if(ajax.status == 200)
            {
               eval(ajax.responseText);
            }
         }
}