Observer Pattern

Observer Pattern

Observer Pattern is commonly use to implement Pub/Sub model.

IObservable Has-A IObservable

WeatherStation Is-A IObservable

PhoneDisplay Is-A Observer

PhoneDisplay Has-A WeatherStation

interface IObservable {
    add(Observer)
    remove(Observer)
    notify(Observer)
}

interface IObserver {
    update()
}


class weatherStation implements Observable {
   
   observers: array;
   
   add (observer:IObserver) {
   
        observers.push(observer);
   }
   
   remove (observer:IObserver) {
        observers.remove(observer);
   }
   
   notify () {
        observers.forEach(function(observer) {
            observer.update();
        });
   }
}

class phoneDisplay implements Observable {
    
    construct(station:WeatherStation) {
        this.station = station;
    }    
    
    update() {
        this.station.getTemp();
        //do something
    }
    
}