I am searching for a solution to merge multiple Observables into a flattened tuple containing scalar values. This functionality is similar to .combineLatest(), but with the added feature that it should emit a new value tuple even if one of the source observables has not yet emitted a value - in this case, it would yield "undefined" in the tuple position corresponding to the non-emitted observable.
For instance:
const s1 = new Subject<string>();
const s2 = new Subject<string>();
Observable.combineWithUndefined(s1, s2).subscribe( ([t1, t2]) => {
console.log(t1.toString() + " " + t2.toString());
});
s1.next("Hello");
s2.next("John");
// expected output:
// Hello undefined
// Hello John