The simplest notification, Subscribe/Publish in Javascript

NotificationMessages.js

// Notification Messages
// This is made by Publish-Subscribe Topics

class YLNotificationMessages {
    constructor () {
        // Event Objects: storing event name and event callback 
        this.events = {};
    }
  
    // Subscribe Event
    subscribe (eventName, callback) {
        if (!this.events[eventName]) {
            // One event name can be used for multiple event callbacks 
            this.events[eventName] = [callback];
        } else {
            // If the event name exists, then add more callbacks to it
            this.events[eventName].push(callback);
        }
    }
  
    // Publish Event with arguments
    publish (eventName, ...args) {
        this.events[eventName] && this.events[eventName].forEach(cb => cb(...args));
    }
  
    // Unsubscribe Event by name and callback
    unsubscribe (eventName, callback) {
        if (this.events[eventName]) {
            // Find the callback in accordance with its event name and remove it from the event list.
            this.events[eventName].filter(cb => cb != callback);
        }
    }
}

// Register the class to Window Objects in Javascript 
window["YLNotificationMessages"] = new YLNotificationMessages();

This is how we subscribe the event

window.YLNotificationMessages.subscribe("ReceiveMessages", function(data) {
     console.log(data);
});

When we publish data and all the subscribers will receive the data

var data = {
     "user_id": 28648,
     "user_name": "jd",
     "user_language": "en",
     "user_uuid": "8b3d1204-e2ee-11e9-9d7c-1f8e47066aae",
     "user_email": "[email protected]",
     "user_avatar": "https://google.com/icon.png"
};
window.YLNotificationMessages.publish("ReceiveMessages", data);