SOURCE

var Ajax=$.ajax({
  'url':'/echo'
});
Ajax.fail(function(){
  console.log('fail!');
});
Ajax.done(
  function(response, status, jqXHR){
    console.log(status);
    console.log(jqXHR);
    document.body.innerHTML='<span><big>成功！,2S后显示</big></span>';
    setTimeout(function(){
    document.body.innerHTML=response;},2000);
  }
)