find

signature: find(predicate: function)
Emit the first item that passes predicate then complete.
💡 If you always want the first item emitted, regardless of condition, try first()!
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Examples
Example 1: Find click inside box, repeat when a click occurs outside of box
( StackBlitz)
// RxJS v6+
import { fromEvent } from 'rxjs';
import { find, repeatWhen, mapTo, startWith, filter } from 'rxjs/operators';
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// elem ref
const status = document.getElementById('status');
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// streams
const clicks$ = fromEvent(document, 'click');
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clicks$
  .pipe(
    find((event: any) => event.target.id === 'box'),
    mapTo('Found!'),
    startWith('Find me!'),
    // reset when click outside box
    repeatWhen(() =>
      clicks$.pipe(filter((event: any) => event.target.id !== 'box'))
    )
  )
  .subscribe(message => (status.innerHTML = message));
Additional Resources
​find 📰 - Official docs
📁 Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/find.ts​

filter

first

Last modified 3yr ago