var oXmlHttp = null;
  var iInterval = 1000;
  var iLastCommentId = -1;
  var divNotification = null;
  
  function checkComments() {
      if (!oXmlHttp) {
          oXmlHttp = zXmlHttp.createRequest();
      } else if (oXmlHttp.readyState != 0) {
          oXmlHttp.abort();
      }    
      
      oXmlHttp.open("get", <CheckComments.php>, true);
      oXmlHttp.onreadystatechange = function () {               
          
          if (oXmlHttp.readyState == 4) {
              if (oXmlHttp.status == 200) {
  
                  var aData = oXmlHttp.responseText.split("||");
                  if (aData[0] != iLastCommentId) {                   
                      
                      iLastCommentId = aData[0];
                      
                      if (iLastCommentId != -1) {                        
                          showNotification(aData[1], aData[2]);
                      }
                      
                  }
                  
                  setTimeout(checkComments, iInterval);             
              }                         
          }
      };    
  
      oXmlHttp.send(null);       
  
  }
  
  function showNotification(sName, sMessage) {
      if (!divNotification) {
          divNotification = document.createElement("div");
          divNotification.className = "notification";
          document.body.appendChild(divNotification);
      }
      
      divNotification.innerHTML = "<strong>New Comment</strong><br />" + sName 
                + " says: " + sMessage + "...<br /><a href=\"ViewComment.php?id=" 
                + iLastCommentId + "\">View</a>";
      divNotification.style.top = document.body.scrollTop + "px";
      divNotification.style.left = document.body.scrollLeft + "px";
      divNotification.style.display = "block";
      setTimeout(function () {
          divNotification.style.display = "none";
      }, 5000);
  }
  
  //if Ajax is enabled, assign event handlers and begin fetching
  window.onload = function () {
      if (zXmlHttp.isSupported()) {
          checkComments();              
      }
  };