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ObserverPattern.js
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class FavoriteYouTubeChannel {
constructor(subscription) {
this.subscription = subscription;
}
uploadNewVideo(title) {
this.subscription.notify(`new video: ${title}`);
}
}
class Subscription {
constructor() {
this.observers = [];
}
subscribe(observer) {
this.observers.push(observer);
}
unsubscribe(observer) {
this.observers = this.observers.filter((obs) => obs !== observer);
}
notify(message) {
this.observers.forEach((observer) => {
observer(message);
});
}
}
const subscriber1 = (data) => {
console.log(data);
}
const subscriber2 = (data) => {
console.log(data);
}
const subscription = new Subscription();
const favoriteYouTubeChannel = new FavoriteYouTubeChannel(subscription);
// subscribe
subscription.subscribe(subscriber1);
subscription.subscribe(subscriber2);
// event trigger!
favoriteYouTubeChannel.uploadNewVideo('Ultimate Prank Bro!');
// unsubscribe
subscription.unsubscribe(subscriber2);
// event trigger!
favoriteYouTubeChannel.uploadNewVideo('Mukbang Seafood!');
/* output
new video: Ultimate Prank Bro!
new video: Ultimate Prank Bro!
new video: Mukbang Seafood!
*/