Exponential backoff example

index.js

const {rxObserver} = require('api/v0.3');
const { timer } = require('rxjs');
const { map, tap, retryWhen, delayWhen } = require('rxjs/operators');

const source$ =
  timer(0, 100).pipe(
    map(val => {
      if (val == 1) {
        throw 'Err';
      }
      return val;
    })
  );

const sourceObserver = rxObserver('source$: value at 0ms, error at 100ms');
const errorsObserver = rxObserver('Errors at');
const retriesObserver = rxObserver('Retries at');
const resultObserver = rxObserver('result$');

const result$ = source$.pipe(
    retryWhen(errors =>
      // here Errors are just events
      errors.pipe(
        // show error messages thread
        map(()=>Date.now()),
        tap(errorsObserver),
        // will restart with increasing delay
        delayWhen((_, index) => timer(index * index * 10)),
        map(()=>Date.now()),
        tap(retriesObserver)
      )
    )
);


source$.subscribe(sourceObserver);
result$.subscribe(resultObserver);