javascript 活动PubSub

Posted 2021-05-03

var events = {
    events: {},
    
    /**
     * Subscribe to an event
     * @param {string} eventName 
     * @param {*} fn 
     */
    on: function(eventName, fn) {
        this.events[eventName] = this.events[eventName] || [];
        this.events[eventName].push(fn);
    },

    /**
     * Unsubscribe from an event
     * @param {string} eventName 
     * @param {*} fn 
     */
    off: function(eventName, fn) {
        if (this.events[eventName]) {
            for (var i = 0; i < this.events[eventName].length; i++) {
                if (this.events[eventName][i] === fn) {
                    this.events[eventName].splice(i, 1);
                    break;
                }
            };
        }
    },

    /**
     * Publish an event
     * @param {string} eventName 
     * @param {*} data 
     */
    emit: function(eventName, data) {
        if (this.events[eventName]) {
            this.events[eventName].forEach(function(fn) {
                fn(data);
            });
        }
    }
};