Ajax类

Ajax = ...{
  xmlhttp: function()...{
    if (window.XMLHttpRequest)    //   Mozilla,   Safari,...
         return  new XMLHttpRequest();          
    else if(window.ActiveXObject)      //   IE
         return   new ActiveXObject("Msxml2.XMLHTTP");
    else
         return   new ActiveXObject('Microsoft.XMLHTTP');
  },
  url:'',
  method:'POST',
  load:'',
  end:'',
  agr:'',
  returnValue:'',
  pars:null,
  request:function()...{  //ajax异步数据更新
   
   var xmlhttp= this.xmlhttp();
   var load=this.load;
   var end=this.end;
   var agr=this.agr;
   xmlhttp.open(this.method,this.url,true);
   xmlhttp.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
   xmlhttp.onreadystatechange=function()...{
         switch (xmlhttp.readyState)
         ...{
         case 1:
           if (typeof(load)=='function')
             ...{
             load();
             }
          else
           eval(load);
          break;
         case 2:

          break;
         case 3:
 
          break;
         case 4:
              if (typeof(end)=='function')
              ...{
             end(xmlhttp);
               }
          else
            eval(end);
            
          break;
         }
        
        
        };
   xmlhttp.send(this.pars);
   this.end='';
  }

 
};