What is the Observer Pattern in TypeScript?

Can you explain the Observer Pattern in TypeScript?

Sure! The Observer Pattern is a behavioral design pattern that allows an object, known as the subject, to maintain a list of its dependents, called observers, and notify them of any state changes.

How do I implement it in TypeScript?

To implement the Observer Pattern in TypeScript, you can create a Subject class that manages observers and a method to notify them of changes. Would you like to see a code example?

Yes, please provide a code example.

Here's a simple implementation:

class Subject {
    private observers: Function[] = [];

    public subscribe(observer: Function) {
        this.observers.push(observer);
    }

    public unsubscribe(observer: Function) {
        this.observers = this.observers.filter(obs => obs !== observer);
    }

    public notify(data: any) {
        this.observers.forEach(observer => observer(data));
    }
}

const subject = new Subject();
const observer1 = (data: any) => console.log(`Observer 1: ${data}`);
subject.subscribe(observer1);
subject.notify('Hello Observers!');

What are some use cases for the Observer Pattern?

Common use cases include implementing event handling systems, data binding in UI frameworks, and managing state changes in applications.