mroderick/PubSubJS

import PubSub from 'pubsub-js'

// or when using CommonJS
const PubSub = require('pubsub-js');

// create a function to subscribe to topics
var mySubscriber = function (msg, data) {
    console.log( msg, data );
};

// add the function to the list of subscribers for a particular topic
// we're keeping the returned token, in order to be able to unsubscribe
// from the topic later on
var token = PubSub.subscribe('MY TOPIC', mySubscriber);

// publish a topic asynchronously
PubSub.publish('MY TOPIC', 'hello world!');

// publish a topic synchronously, which is faster in some environments,
// but will get confusing when one topic triggers new topics in the
// same execution chain
// USE WITH CAUTION, HERE BE DRAGONS!!!
PubSub.publishSync('MY TOPIC', 'hello world!');

// create a function to receive the topic
var mySubscriber = function (msg, data) {
    console.log(msg, data);
};

// add the function to the list of subscribers to a particular topic
// we're keeping the returned token, in order to be able to unsubscribe
// from the topic later on
var token = PubSub.subscribe('MY TOPIC', mySubscriber);

// unsubscribe this subscriber from this topic
PubSub.unsubscribe(token);

// create a function to receive the topic
var mySubscriber = function(msg, data) {
    console.log(msg, data);
};

// unsubscribe mySubscriber from ALL topics
PubSub.unsubscribe(mySubscriber);

PubSub.subscribe('a', myFunc1);
PubSub.subscribe('a.b', myFunc2);
PubSub.subscribe('a.b.c', myFunc3);

PubSub.unsubscribe('a.b');
// no further notifications for 'a.b' and 'a.b.c' topics
// notifications for 'a' will still get published

PubSub.clearAllSubscriptions();
// all subscriptions are removed

PubSub.getSubscriptions('token');
// subscriptions by token from all topics

PubSub.countSubscriptions('token');
// count by token from all topics

// isPublished is a boolean that represents if any subscribers was registered for this topic
var isPublished = PubSub.publish('a');

// token will be false if something went wrong and subscriber was not registered
var token = PubSub.subscribe('MY TOPIC', mySubscriber); 

// create a subscriber to receive all topics from a hierarchy of topics
var myToplevelSubscriber = function (msg, data) {
    console.log('top level: ', msg, data);
}

// subscribe to all topics in the 'car' hierarchy
PubSub.subscribe('car', myToplevelSubscriber);

// create a subscriber to receive only leaf topic from hierarchy op topics
var mySpecificSubscriber = function (msg, data) {
    console.log('specific: ', msg, data);
}

// subscribe only to 'car.drive' topics
PubSub.subscribe('car.drive', mySpecificSubscriber);

// Publish some topics
PubSub.publish('car.purchase', {name: 'my new car'});
PubSub.publish('car.drive', {speed: '14'});
PubSub.publish('car.sell', {newOwner: 'someone else'});

// In this scenario, myToplevelSubscriber will be called for all
// topics, three times in total
// But, mySpecificSubscriber will only be called once, as it only
// subscribes to the 'car.drive' topic

// 👎 Bad usage
PubSub.subscribe('hello', function (msg, data) {
	console.log(data)
});

PubSub.publish('hello', 'world');

// 👍 Better usage
var MY_TOPIC = 'hello';
PubSub.subscribe(MY_TOPIC, function (msg, data) {
	console.log(data)
});

PubSub.publish(MY_TOPIC, 'world');

// event-types.js
export const MY_TOPIC = Symbol('MY_TOPIC')

// somefile.js
import { MY_TOPIC } from './event-types.js'
PubSub.subscribe(MY_TOPIC, function (msg, data) {
	console.log(data)
});

PubSub.publish(MY_TOPIC, 'world');

PubSub.immediateExceptions = true;