Compare RxJS Observables with Promises.
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Understand the problem
rxjsobservables
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Attempt it yourself
Sketch your approach before reading the solution — that's what interviews test.
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Study the solution
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Give it an honest attempt first — then compare your thinking with the full walkthrough.
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Read the code
One value vs a stream
import { Observable, interval, map, take } from 'rxjs';
// Promise — runs now, resolves once
const p: Promise<number> = Promise.resolve(42);
p.then(v => console.log('promise:', v));
// Observable — lazy until subscribe, emits a stream, cancelable
const stream$: Observable<number> = interval(1000).pipe(
map(n => n * 10),
take(3), // 0, 10, 20 then complete
);
const sub = stream$.subscribe(v => console.log('observable:', v));
// sub.unsubscribe(); // cancels the work05
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