Observables Explained for Angular Beginners

Angular uses Observables everywhere (HTTP, Router, Forms). Think of an Observable like a stream of values over time.

Simple mental model

• A Promise gives you one value later.
• An Observable can give you many values over time.

Observable stream picture

flowchart LR
  A[Observable] --> B[Value 1]
  A --> C[Value 2]
  A --> D[Value 3]

Example: interval stream

import { interval } from 'rxjs';

interval(1000).subscribe(n => {
  console.log('Tick:', n);
});

This logs a number every second.

Why Angular likes Observables

• cancelable (unsubscribe)
• supports streaming updates
• powerful operators (map, filter, switchMap)

Important: unsubscribe (basic rule)

If you subscribe to long-lived streams, clean up in ngOnDestroy.
HTTP calls complete automatically, so they usually do not need manual unsubscribe.

Next: Use async pipe to avoid manual subscribe and unsubscribe.