PubSub.js

export default class PubSub {
    // 订阅
    subscribe(message, fn) {
        if (typeof fn !== 'function') {
            return false;
        }
        if (!PubSub.messages.hasOwnProperty(message)) {
            PubSub.messages[message] = {};
        }
        const token = `uid_${String(++PubSub.lastUid)}`;
        PubSub.messages[message][token] = fn;
        return token;
    }

    // 发布
    publish(message, data) {
        if (!this.messageHasSubscribers(message)) {
            return false;
        }
        const deliver = this.deliverFunction(message, data);
        setTimeout(deliver, 0);
    }

    // 生成函数
    deliverFunction(message, data) {
        return function () {
            const subscribers = PubSub.messages[message];
            for (const s in subscribers) {
                if (subscribers.hasOwnProperty(s)) {
                    subscribers[s](data);
                }
            }
        };
    }

    // 判断对象的实例上面是否有token的属性
    hasKeys(obj) {
        return Object.keys(obj).find(item => /^uid_\d+/.test(item)) !== undefined;
    }

    // 判断消息是否有订阅者
    messageHasSubscribers(message) {
        return PubSub.messages.hasOwnProperty(message) && this.hasKeys(PubSub.messages[message]);
    }

    // 取消所有该事件的订阅项
    clearAllSubscribeOptions(value) {
        const message = PubSub.messages[value];
        for (const t in message) {
            if (message.hasOwnProperty(t)) {
                delete message[t];
            }
        }
    }

    // 取消订阅
    unsubscribe(value) {

        // 判断传入的参数是消息类型还是 token 还是函数
        const isMessage = typeof value === 'string' && PubSub.messages.hasOwnProperty(value);
        const isToken = typeof value === 'string' && !PubSub.messages.hasOwnProperty(value);
        const isFunction = typeof value === 'function';

        if (isMessage) {
            this.clearAllSubscribeOptions(value);
            return true;
        }

        for (const m in PubSub.messages) {
            if (PubSub.messages.hasOwnProperty(m)) {
                const message = PubSub.messages[m];
                if (isToken && message[value]) {
                    delete message[value];
                    return true;
                }

                if (isFunction) {
                    for (const t in message) {
                        if (message.hasOwnProperty(t) && message[t] === value) {
                            delete message[t];
                            return true;
                        }
                    }
                }
            }
        }
    }
  }

// class 共有的属性
PubSub.messages = {};
PubSub.lastUid = -1;