Angular 2 limit parallel http calls

Question

I've got an Angular 2 app, which fetches a varying number of ids from a server, and then, for each id makes another REST call in a forkJoin.

However, the amount of ids can go up to a few hundreds, which might be problematic when suddenly making several hundred REST calls in parallel.

Is there a way of limiting the number of parallel calls when using RxJs and the forkJoin operator?

Answer 1

Onw way would be to use bufferCount:

Rx.Observable.from([1,2,3,4,5,6,7,8])
  .bufferCount(3)
  .concatMap(items => {
    console.log('ConcatMap', items);
    let tasks = items.map(item => Rx.Observable.timer(Math.random() * 1000).do(() => console.log(item, 'ready')));
    return Rx.Observable.forkJoin(...tasks);
  })
  .subscribe()

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