async error handler in RxJS

readme.md

Example for RxJS - Using an observable in catchError block https://stackoverflow.com/questions/54824325/rxjs-using-an-observable-in-catcherror-block/

Run at https://thinkrx.io/gist/65d073b7f78173f5cc49118087187a35

index.js

const { rxObserver } = require('api/v0.3');
const { timer, throwError } = require('rxjs');
const { mapTo, tap, catchError, switchMap } = require('rxjs/operators');

const error$ = timer(10).pipe(
    switchMap(() => throwError('X'))
  );

const omittedCatch$ = error$
  .pipe(
    catchError(err => {
      testCall('omitted', err);
      return timer(10).pipe(mapTo('o'));
    })
  );

const workingCatch$ = error$
  .pipe(
    catchError(err => testCall('catched', err))
  );

error$.subscribe(rxObserver('Error'));
omittedCatch$.subscribe(rxObserver('Omitted'));
workingCatch$.subscribe(rxObserver('Working'));

function testCall(name, value){
  return timer(10)
    .pipe(
      mapTo(value),
      tap(rxObserver('> ' + name))
    )
}

maksud dari const?