Combining two observables, skip first value emitted by one observable if it is null

I am listening to two observables. In all cases, I want to filter out when obs2 is null.

Now, obs1 can emit a string or a null value. I want to listen to all values of obs1 except the case when its first emitted value is null.

I can probably use a boolean to check if it is obs1's first emitted value, but I was wondering if there is an operator to filter the first value only? Any help would be appreciated.

        combineLatest([this.obs1$, this.obs2$]).pipe(
            // TODO: filter out first value of obs if it is null
            filter(([, obs2]) => obs2!= null),
        )
        .subscribe(([obs1, obs2]) => {
            // do something
        });

The filter operator provides the index as the second param, which can be used to determine if its the first emission or not. In your case it sounds like you want to apply a filter to obs1$ to prevent emitting the first emission if it's null. The also, apply a filter on the combineLatest result whenever obs2$ is null.

Something like this should work:

combineLatest([
  this.obs1$.pipe(filter((obs1, i) => i>0 || !!obs1), 
  this.obs2$,
]).pipe(
  filter(([, obs2]) => !!obs2
).subscribe(([obs1, obs2]) => {
  // do something
});