in RxJava there is the Observable.toBlocking() operator to retrieve the data of the observable synchronously. I can not find a similiar operator for RxJS. I want to use this operator to improve my code with Rx and without using another functional programming library...
see schedulers
If you do not provide the scheduler, RxJS will pick a default scheduler by using the principle of least concurrency. This means that the scheduler which introduces the least amount of concurrency that satisfies the needs of the operator is chosen.
As long as you don't specify a scheduler RxJS itself picks a blocking scheduler / resolves the observable synchronously (immediate scheduler) as you can see in this jsbin - the first observable completes before the second is started.
If you want to control the level of concurrency explicitely, you could do this by passing a specific scheduler to the operator that supports this option.