发布/订阅，是一种由两个部分构成:发布者和订阅者的消息传递模式。发布者将消息发布到特定频道，而订阅者接听频道，当频道上有消息发布时将接收到通知。
实现Pub/Sub模式代码：
var PubSub = {
//订阅
subscribe : function(ev,callback){
this._callback || (this._callback = {});
(this._callback[ev] || (this._callback[ev] = [])).push(callback);
return this;
},
//取消订阅
unsubscribe : function(ev){
if(!this._callback || !this._callback[ev]){
return this;
}
this._callback[ev] = null;
delete this._callback[ev];
return this;
},
//发布
publish : function(){
var callback, list, i, length, args = [].slice.call(arguments,0), ev = args.shift();
if(!(callback = this._callback) || !(list = this._callback[ev])){
return this;
}
for(i = 0, length = list.length; i < length; i++){
list[i].apply(this, args);
}
return this;
}
};
PubSub.subscribe('wen',function(){alert('Wen!!!');}).publish('wen').unsubscribe('wen').publish('wen');