原生Javascript封装的一个AJAX函数分享

       root.url=ops.url;
       root.type=ops.type||"responseText";
       root.method=ops.method||"GET";
       root.async=ops.async||true;    
       root.data=ops.data||{};
       root.complete=ops.complete||function (){};
       root.success=ops.success||function(){};
       root.error= ops.error||function(s){alert(root.url+"->status:"+s+"error!")};
       root.abort=req.abort;
       root.setData=function (data){
           for(vardindata){
               root.data[d]=data[d];
           }
       }
       root.send=function (){
           vardatastring=formatData(root.data),
           sendstring,get=false,
           async=root.async,
           complete=root.complete,
           method=root.method,
           type=root.type;
           if(method==="GET"){
               root.url+="?"+datastring;
               get=true;
           }
           req.open(method,root.url,async);
           if(!get){
               req.setRequestHeader("Content-type","application/x-www-form-urlencoded");
               sendstring=datastring;
           }      

           //在send之前重置onreadystatechange方法,否则会出现新的同步请求会执行两次成功回调(chrome等在同步请求时也会执行onreadystatechange)
           req.onreadystatechange=async?function (){
               //console.log("asynctrue");
               if(req.readyState==4){
                   complete();
                   if(req.status==200){
                       root.success(req[type]);
                   }else{
                       root.error(req.status);
                   }                  
               }
           }:null;
           req.send(sendstring);
           if(!async){
               //console.log("asyncfalse");
               complete();
               root.success(req[type]);
           }
       }
       root.url&&root.send();       
   };
   returnfunction(ops){returnnewAJAX(ops);}   
}();