What are Hot Observables and Cold Observables?

Cold Observables are observables where data is produced inside the Observable. It can be treated as a unicast.

const obs$ = new Obserable((observer) => {
    observer.next(Math.random());
});
obs$.subscribe((data) => console.log(data)); // prints different value
obs$.subscribe((data) => console.log(data)); // prints different value

Hot Observables are observables where data is produced outside the Observable. It can be treated as a multicast.

const data = 5;
const obs$ = new Obserable((observer) => {
    observer.next(data);
});
obs$.subscribe((data) => console.log(data)); // prints 5
obs$.subscribe((data) => console.log(data)); // prints 5

Ram
November 4, 2020
Interview Q&A

Cold Observables are observables where data is produced inside the Observable. It can be treated as a unicast.

const obs$ = new Obserable((observer) => {
    observer.next(Math.random());
});
obs$.subscribe((data) => console.log(data)); // prints different value
obs$.subscribe((data) => console.log(data)); // prints different value

Hot Observables are observables where data is produced outside the Observable. It can be treated as a multicast.

const data = 5;
const obs$ = new Obserable((observer) => {
    observer.next(data);
});
obs$.subscribe((data) => console.log(data)); // prints 5
obs$.subscribe((data) => console.log(data)); // prints 5

Ram

I'm a full-stack developer and a software enthusiast who likes to play around with cloud and tech stack out of curiosity. You can connect with me on Medium, Twitter or LinkedIn.