function setbodywidth()
      {
        document.body.style.width = screen.width - 80 ;
      }
      
      function createAjaxHttp()
      {
      var obj;
      if(window.XMLHttpRequest) 
       { //Mozilla 浏览器 
        obj = new XMLHttpRequest(); 
       } 
       else if (window.ActiveXObject) { // IE浏览器 
              try { 
                  obj = new ActiveXObject("Msxml2.XMLHTTP"); 
                 } catch(e){ 
                            try{ 
                              obj = new ActiveXObject("Microsoft.XMLHTTP"); 
                            } catch (e) {} 
                 } 
      } 
       return obj;
    
      }
      
        //利用异步更新来计算对应订单的累计 
   function AjaxStart(str_URL,RST_id )
   {
    xml_obj =  createAjaxHttp();
    Rst_target_id = RST_id ;
    xml_obj.open("GET", str_URL, true);  
    xml_obj.onreadystatechange = GetValue; //响应函数
    xml_obj.send(null); // 发送请求 
   }
   
   function GetValue()
   {
     if(xml_obj.readyState == 4 && xml_obj.status == 200)
     {
       //计算完成
        //alert(xml_obj.responseText); 
        if (document.getElementById(Rst_target_id))
                      document.getElementById(Rst_target_id).value = xml_obj.responseText;
     }
 }