Defer 대상 의 간단 한 실현

개선 할 점:
 1. 여러 Defer 대상 을 동시에 사용 할 수 없습니다. 2. 실현 의 불완전 함.프레젠테이션 주소:http://runjs.cn/code/uh9uvnxk 코드 는 다음 과 같 습 니 다:

// Defer        
//      Defer  done、fail、then、always  
(function(window){
  var Defer = function(){
    return Defer.prototype.init();
  }
  Defer.prototype.init = function(){
    this.state = 'init';
    this.queue = {
      success:[],
      fail:[],
      always:[]
    }
    return this;
  }
  Defer.prototype.resolve = function(){
    this.state = 'resolved';
    this.fire();
  }
  Defer.prototype.reject = function(){
    this.state = 'rejected';
    this.fire();
  }
  Defer.prototype.fire = function(){
    if(this.state == 'resolved'){
      var i = 0;
      for(;i < this.queue.success.length; i++){
        this.queue.success[i]();
      }
    }
    else if(this.state == 'rejected'){
      var i = 0;
      for(;i < this.queue.fail.length; i++)
        this.queue.fail[i]();
    }
    var i = 0;
    for(; i < this.queue.always.length; i++){
      this.queue.always[i]();
    }
  }
  Defer.prototype.promise = function(){
    var self = this;
    return{
      done: function(callback){
        self.queue.success.push(callback);
        //         
        return this;
      },
      fail: function(callback){
        self.queue.fail.push(callback);
        return this;
      },
      then: function(doneCallback, failCallback){
        self.queue.success.push(doneCallback);
        self.queue.fail.push(failCallback);
        return this;
      },
      always: function(callback){
        self.queue.always.push(callback);
        return this;
      }
    }
  }  
  window.Defer = Defer;
})(window)


//
// test
// 

function test(){
  var defer = Defer();
  setTimeout(function(){
    alert('Success');
    defer.resolve();
    // defer.reject();
  }, 1000);
  return defer.promise();
}

test().done(function(){
  alert('done 01');
}).done(function(){
  alert('done 02')
}).done(function(){
  alert('done 03')
}).fail(function(){
  alert('fail 01')
}).fail(function(){
  alert('fail 02')
}).always(function(){
  alert('always 01')
}).always(function(){
  alert('always 02')
})

over