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rxjsrxjs-observablesrxjs-pipeable-operators

Altering combineLatest to emit the result without awaiting other observables

I have this rxjs code where cobineLatest is used

cobineLatest(
  this.controls.toArray().map(c => c.changeEvent.asObservable())
).subscribe(x => {
  console.log(x);
});

The thing is that there won't be any result in subscription until all observables emits, I wonder how would you change that behavior so it will start emitting even if one single observable emits?

Solution

  • I suggest you to just pipe the single observables to start with null. This way you ensure that each observable has emitted at least one value:

    cobineLatest(
  this.controls.toArray().map(c => c.changeEvent.asObservable().pipe(startWith(null)))
).subscribe(x => {
  console.log(x);
});