Rxjs: Observable.combineLatest vs Observable.forkJoin

Not only does forkJoin require all input observables to be completed, but it also returns an observable that produces a single value that is an array of the last values produced by the input observables. In other words, it waits until the last input observable completes, and then produces a single value and completes.

In contrast, combineLatest returns an Observable that produces a new value every time the input observables do, once all input observables have produced at least one value. This means it could have infinite values and may not complete. It also means that the input observables don't have to complete before producing a value.

forkJoin - When all observables complete, emit the last emitted value from each.

combineLatest - When any observable emits a value, emit the latest value from each.

Usage is pretty similar, but you shouldn't forget to unsubscribe from combineLatest unlike forkJoin.