index.js

/**
 * Importing pusher
 */
var Pusher = require('pusher-js');

/**
 * VuePusher class.
 *
 * @param {String} api_key
 * @param {Object} options
 */
function VuePusher (Pusher, api_key, options) {
    this.pusher   = new Pusher(api_key, options);
    this.channels = [];
}

/**
 * Subscribe to the given channel and give a fallback to bind events to the channel.
 *
 * @param  {String}   channel_name
 * @param  {Function} callback
 */
VuePusher.prototype.subscribe = function (channel_name, callback) {
    var channel = this.pusher.subscribe(channel_name);

    if (! this.channels.includes(channel)) {
        this.channels.push(channel_name);
    }

    callback(channel);
};

/**
 * Unsubscribe from the given channel.
 *
 * @param  {String} channel
 */
VuePusher.prototype.unsubscribe = function (channel) {
    this.pusher.unsubscribe(channel);
};

/**
 * Return all the chanels.
 *
 * @return {Array}
 */
VuePusher.prototype.getChannels = function () {
    return this.channels;
};

module.exports = {
    install: function (Vue, Pusher, options) {
        var pusher = new VuePusher(Pusher, options.api_key, options.options);

        Vue.prototype.pusher  = pusher;
        Vue.prototype.$pusher = pusher.pusher; // Just in case they want to manage it themselves.
    }
};