Swipe To Refresh

By adamlubek

This recipe demonstrates RxJS implementation of swipe to refresh functionality. Inspired by @BenLesh RxJs talks.

Ultimate RxJS

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';
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