RxJS sequence equivalent to promise.then()?

Question

I used to develop a lot with promise and now I am moving to RxJS. The doc of RxJS doesn\'t provide a very clear example on how to move from promise chain to observer sequenc

Answer 1

if getPromise function is in a middle of a stream pipe you should simple wrap it into one of functions mergeMap, switchMap or concatMap (usually mergeMap):

stream$.pipe(
   mergeMap(data => getPromise(data)),
   filter(...),
   map(...)
 ).subscribe(...);

if you want to start your stream with getPromise() then wrap it into from function:

import {from} from 'rxjs';

from(getPromise()).pipe(
   filter(...)
   map(...)
).subscribe(...);