Interview: mergeMap() concurrency argument

Use mergeMap with a concurrency of 2 to load the ids.

1. Solve the task in the editor — no long theory.
2. Run the check and compare your output with the expected result.
3. Stuck? Open the solution and carry the approach into your own code.

const { from, of, mergeMap } = Rx;

const load = id => of('item-' + id);

const result$ = from([1, 2, 3]).pipe(
  mergeMap(id => load(id), 2)
);

result$.subscribe(value => console.log(value));