RxJS version: 5.5.2
Working with an array const v = [1, 2, 3];
The goal is to convert this array into a Subject initially acting like an Observable until all values (1, 2, 3) are consumed. After that, it should behave like a Subject.
The challenge lies in using reduce on the initial values of v = [1, 2, 3], and then switching to scan each time a new value is added by the Subject.
Current code snippet:
const v = [1, 2, 3];
const sub = new Subject<number>();
const observable = sub.pipe(
startWith(0),
concatMap(x => from(v)),
scan((a, b) => {
return a + b;
}, 0),
);
observable.subscribe(x => console.log(x));
When using scan, the following sequence is printed to the console:
1
3
6
The desired output is just the last value 6. Substituting scan with reduce achieves this, but only if the subject is completed (making it unable to receive future values).
To address this, the objective is to print 10 when a new value is sent by the subject through sub.next(4);, and so forth.