Last active
March 28, 2019 13:33
-
-
Save wolfpilot/055d1d486efac06c00c93ff7900b8bd3 to your computer and use it in GitHub Desktop.
PubSub singleton (ES6)
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| /** | |
| * Pub / sub (Observer) decoupling function | |
| * | |
| * Based on Addy Osmani's Publish/Subscribe example | |
| * https://addyosmani.com/resources/essentialjsdesignpatterns/book/#observerpatternjavascript | |
| */ | |
| class PubSub { | |
| /** | |
| * Constructor | |
| */ | |
| constructor() { | |
| this.topics = {}; | |
| this.subID = -1; | |
| } | |
| /** | |
| * Publish event to all subscribers registered to the specified topic | |
| * @param {String} topic - Topic to be published to | |
| * @param {Any} args - Arguments passed to the subscribers | |
| */ | |
| publish(topic, args) { | |
| if (!this.topics[topic]) { return; } | |
| for (const subscriber of this.topics[topic]) { | |
| subscriber.cb(topic, args); | |
| } | |
| } | |
| /** | |
| * Unsubscribe listener from topic | |
| * @param {Number} token - Unique token associated with subscriber | |
| */ | |
| unsubscribe(token) { | |
| if (!this.topics) { return; } | |
| const subscriptions = new Map(Object.entries(this.topics)); | |
| // Check existing subscriptions for matching subscriber ID | |
| subscriptions.forEach((subcribers, topic) => { | |
| const subID = subcribers.findIndex(sub => sub.token === token); | |
| if (subID) { | |
| this.topics[topic].splice(subID, 1); | |
| return; | |
| } | |
| }); | |
| } | |
| /** | |
| * Subscribe listener to topic | |
| * @param {String} topic - Topic to subscribe to | |
| * @param {Function} cb - Function to be called when new topic is published | |
| * @returns {Number} - Unique token used to identify the function | |
| */ | |
| subscribe(topic, cb) { | |
| this.subID += 1; | |
| const token = this.subID; | |
| this.topics[topic] = this.topics[topic] || []; | |
| // Store both token and function | |
| this.topics[topic].push({ | |
| token: token, | |
| cb: cb | |
| }); | |
| return token; | |
| } | |
| } | |
| // Export as Singleton | |
| export default new PubSub(); |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment