This is an implementation of Service Observer Pattern in AngularJS (1.x) using ES6.

AngularJS-Service-Observer-Pattern-in-ES6.js

export var ObserverService = (function(){
  
  // MUST be an object
  var data = {};
  
  return class ObserverService {
  
    constructor () {}
  
    api() {
      data = {
        newValue: new Date()
      }
    }
  
    getData() {
      return data;
    }
  
  };
  
}());