手写一个观察者，发布订阅模式

[wengjq]

var pubsub = {};

(function(q) {

    var topics = {},
        subUid = -1;

    // 使用特定主题名称和参数（如要传递的数据）发布事件
    q.publish = function(topic, args) {
        if (!topics[topic]) {
            return false;
        }

        var subscribers = topics[topic],
            len = subscribers ? subscribers.length : 0;

        while (len--) {
            subscribers[len].func( topic, args );
        }

        return this;
    };

    // 当观察到话题/事件时，用特定的话题名称和回调函数来订阅事件
    q.subscribe = function(topic, func) {
        if (!topics[topic]) {
            topics[topic] = [];
        }

        var token = ( ++subUid ).toString();

        topics[topic].push({
            token: token,
            func: func
        });

        return token;
    };

    // 根据对订阅的标记化引用，取消订阅特定主题
    q.unsubscribe = function(token) {
        for (var m in topics) {
            if (topics[m]) {
                for (var i = 0, j = topics[m].length; i < j; i++) {
                    if (topics[m][i].token === token) {
                        topics[m].splice( i, 1 );
                        return token;
                    }
                }
            }
        }

        return this;
    };
}(pubsub));

[SoftwareEngineerPalace]

文不对题