笔记：一个蛋疼的XHR回调函数

function xhrCallback(xhr, resolver){
return (function(){
var state = xhr.readyState;
var status = xhr.status;
resolver[state] ? (resolver[state][status] ? resolver[state][status].call(xhr) : (resolver[state].$ && resolver[state].$.call(xhr)), resolver[state]._ && resolver[state]._.call(xhr)) : (resolver.$ && resolver.$.call(xhr));
resolver._ && resolver._.call(xhr);
});
}

用法：

  var xhr = new XHR;
  xhr.open("GET", "http://yoursite/", true);
  xhr.onreadystatechange = xhrCallback(xhr, { 4 : { 200 : (function(){
    alert("Hello, Web!");
  }), $ : (function(){
    alert("Oops!");
  }), _ : (function(){
    document.write("Mission accomplished");
  }) } });

  xhr.send(null);