Using AJAX by Post Methos

Using AJAX by Post Methos 

function AjaxPostCall(URL,divId,params,append){
  var xmlHttp;
  try
    {
    xmlHttp=new XMLHttpRequest();
    }catch (e) {
        try{
      xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
       }catch (e){
       try{
        xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
        }catch (e){
 return false;
        }
      }
    }
    xmlHttp.onreadystatechange=function()
      {
      if(xmlHttp.readyState==4)
        { 
   if(append=="Y"){
         document.getElementById(divId).innerHTML=document.getElementById(divId).innerHTML+xmlHttp.responseText;
   }else{
   document.getElementById(divId).innerHTML=xmlHttp.responseText; 
   }
        }
      }
    xmlHttp.open("POST",URL,true);
 xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    xmlHttp.send(params);
}