不使用jquery实现Deferred对象

Question

我想在不使用jQuery的情况下实现基本的Deferred对象.在这里,我将仅实现已完成和失败的回调,具有解析和拒绝功能.以及promise与此功能相关的课程关联方法.

我在纯js(编辑)中执行以下实现:

function Deferred() {
    var d = {};
    d.resolve = function() {
        d.done(arguments);
    }
    d.reject = function() {
        d.fail(arguments);
    }
    d.promise = function() {
        var x = {};
        x.done = function(args) {
            return args;
        }
        x.fail = function(args) {
            return args;
        }
        return x;
    }
    return d;
}


var v;

var setVal = function() {
    var d = new Deferred();
    setTimeout(function() {
        v = 'a value';
        d.resolve(this);
    }, 5000);
    return d.promise();
};

setVal().done(function() {
    console.log('all done :' + v);
});

但上面给出了错误: Object #<Object> has no method 'fail'

我知道返回的对象'd'的Deferred()函数没有方法done().如果我从这返回d.promise Deferred()将没有解决和拒绝功能.

请指出我为实现Deferred对象的简单目标所犯的错误.

这是我正在做的小提琴:http://jsfiddle.net/SyEmK/14/

Answer 1

function Deferred(){
  this._done = [];
  this._fail = [];
}
Deferred.prototype = {
  execute: function(list, args){
    var i = list.length;

    // convert arguments to an array
    // so they can be sent to the
    // callbacks via the apply method
    args = Array.prototype.slice.call(args);

    while(i--) list[i].apply(null, args);
  },
  resolve: function(){
    this.execute(this._done, arguments);
  },
  reject: function(){
    this.execute(this._fail, arguments);
  }, 
  done: function(callback){
    this._done.push(callback);
  },
  fail: function(callback){
    this._fail.push(callback);
  }  
}


var v;

var setVal = function() {
    var d = new Deferred();
    setTimeout(function() {
        v = 'a value';
        d.resolve(this);
    }, 5000);
    return d;
};

setVal().done(function() {
    console.log('all done :' + v);
});