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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 | 3x 3x | import { Observable, Subject, debounceTime, filter } from 'rxjs';
export type IntersectionStatus = 'Visible' | 'Pending' | 'NotVisible';
export const fromIntersectionObserver = (
element: HTMLElement,
config: IntersectionObserverInit = {
root: undefined,
rootMargin: '0px',
threshold: undefined,
},
debounce = 0
) =>
new Observable<IntersectionStatus>(subscriber => {
const subject$ = new Subject<{
entry: IntersectionObserverEntry;
observer: IntersectionObserver;
}>();
const intersectionObserver = new IntersectionObserver((entries, observer) => {
entries.forEach(entry => subject$.next({ entry, observer }));
}, config);
subject$.subscribe(() => {
subscriber.next('Pending');
});
subject$.pipe(debounceTime(debounce), filter(Boolean)).subscribe(async ({ entry }) => {
const isEntryVisible = await isVisible(entry.target as HTMLElement);
if (isEntryVisible) {
subscriber.next('Visible');
} else {
subscriber.next('NotVisible');
}
});
intersectionObserver.observe(element);
return {
unsubscribe() {
intersectionObserver.disconnect();
// eslint-disable-next-line ban/ban, rxjs/no-subject-unsubscribe
subject$.unsubscribe();
},
};
});
async function isVisible(element: HTMLElement) {
return new Promise(resolve => {
const observer = new IntersectionObserver(([entry]) => {
resolve(entry.isIntersecting);
observer.disconnect();
});
observer.observe(element);
});
}
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