js观察者模式

var pubsub = (function(){
    var q = {}
        topics = {},
        subUid = -1;
    //发布消息
    q.publish = function(topic, args) {
        if(!topics[topic]) {return;}
        var subs = topics[topic],
            len = subs.length;
        while(len--) {
            subs[len].func(topic, args);
        }
        return this;
    };
    //订阅事件
    q.subscribe = function(topic, func) {
        topics[topic] = topics[topic] ? topics[topic] : [];
        var token = (++subUid).toString();
        topics[topic].push({
            token : token,
            func : func
        });
        return token;
    };
    //取消订阅
    q.canclesub=function(subtoken){
         for (var m in topics) {
            if (topics[m]) {
                for (var i = 0; i < topics[m].length; i++) {
                    if (topics[m][i].token === subtoken) {
                        topics[m].splice(i, 1);
                        return subtoken;
                    }
                }
            }
        }
        return false;  
    }
    return q;
})();
//触发的事件
var logmsg = function(topics, data) {
    console.log("logging:" + topics + ":" + data);
}
//红眼睛订阅 'wolfcoming'
var a = pubsub.subscribe('wolfcoming', logmsg);
//长耳朵订阅 'wolfcoming'
var b = pubsub.subscribe('wolfcoming', logmsg);
//短尾巴订阅 'wolfcoming'
var c = pubsub.subscribe('wolfcoming', logmsg);
//发布消息狼来了
pubsub.publish('wolfcoming', '狼来了');
//兔妈妈回来了兔宝宝退订
pubsub.canclesub(a);
pubsub.canclesub(b);
pubsub.canclesub(c);
//发布消息狼来了
pubsub.publish('wolfcoming', '狼来了');