问异步调用Html.BeginForm

EN

var statuschecker=setInterval(){
    var rq=xmlHTTPRequestObject();
    rq.open('GET','importstatus.aspx',true);
    rq.onreadystatechange=function(){
      if (rq.readyState==4&&rq.status==200){
        if (rq.responseText=='2'){
          clearInterval(statuschecker); //stop the updater
          statuschecker=null; //prevent memory leak
          return;
        }

        if (rq.responseText=='1'){
          //display that it's still being uploaded
        }
      }//xhr status
    }

    rq.send(null);
}, 1000); //poll every second