Swipe To Refresh

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Swipe To Refresh
By adamlubek​
This recipe demonstrates RxJS implementation of swipe to refresh functionality. Inspired by @BenLesh RxJs talks.
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Example Code
( StackBlitz )
Swipe to Refresh
index.ts
// RxJS v6+
import { fromEvent, iif, of, pipe } from 'rxjs';
import {
  finalize,
  mergeMap,
  takeUntil,
  takeWhile,
  repeat,
  map,
  tap,
  exhaustMap,
  delay
} from 'rxjs/operators';
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const setRefreshPos = y =>
  (document.getElementById('refresh').style.top = `${y}px`);
const resetRefresh = () => setRefreshPos(10);
const setData = data => (document.getElementById('data').innerText = data);
​
const fakeRequest = () =>
  of(new Date().toUTCString()).pipe(
    tap(_ => console.log('request')),
    delay(1000)
  );
​
const takeUntilMouseUpOrRefresh$ = pipe(
  takeUntil(fromEvent(document, 'mouseup')),
  takeWhile(y => y < 110)
);
const moveDot = y => of(y).pipe(tap(setRefreshPos));
const refresh$ = of({}).pipe(
  tap(resetRefresh),
  tap(e => setData('...refreshing...')),
  exhaustMap(_ => fakeRequest()),
  tap(setData)
);
​
fromEvent(document, 'mousedown')
  .pipe(
    mergeMap(_ => fromEvent(document, 'mousemove')),
    map((e: MouseEvent) => e.clientY),
    takeUntilMouseUpOrRefresh$,
    finalize(resetRefresh),
    exhaustMap(y => iif(() => y < 100, moveDot(y), refresh$)),
    finalize(() => console.log('end')),
    repeat()
  )
  .subscribe();
html
<style>
  #refresh {
    position: absolute;
    width: 20px;
    height: 20px;
    background: grey;
    border-radius: 50%;
    left: 50%;
  }
​
  #point {
    position: absolute;
    width: 10px;
    height: 10px;
    background: lightgrey;
    border-radius: 50%;
    left: 51%;
    top: 105px;
  }
​
  #data {
    position: absolute;
    top: 150px;
  }
</style>
​
<div id='refresh'></div>
<div id='point'></div>
<div id='data'>Swipe gray dot down to get latest date/time</div>
Operators Used
​delay​
​exhaustMap​
​finalize​
​fromEvent​
​iif​
​map​
​mergeMap​
​of​
​repeat​
​takeUntil​
​takeWhile​
​tap​
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Outline
Example Code
index.ts
Operators Used