React hooks for working with RxJS observables.

Installation

npm install use-observable-hooks

API

Full API documentation is available at useobservablehooks.com.

useObservable

Subscribe to an RxJS Observable and receive the current value and any error.

import { useObservable } from 'use-observable-hooks';
import { interval } from 'rxjs';

function Timer() {
  const [count, error] = useObservable(interval(1000));

  return <div>Count: {count ?? 'Loading...'}</div>;
}

With RxJS operators:

import { useObservable } from 'use-observable-hooks';
import { interval } from 'rxjs';
import { map, filter } from 'rxjs/operators';

function EvenNumbers() {
  const [evenCount] = useObservable(
    interval(1000),
    filter((n) => n % 2 === 0),
    map((n) => n * 10)
  );

  return <div>Even count x10: {evenCount ?? 'Waiting...'}</div>;
}

useBehaviorSubject

Use an RxJS BehaviorSubject with state management capabilities. A BehaviorSubject always has a current value.

import { useBehaviorSubject } from 'use-observable-hooks';

function Counter() {
  const [count, setCount, error] = useBehaviorSubject(0);

  return (
    <button onClick={() => setCount(count + 1)}>
      Count: {count}
    </button>
  );
}

With RxJS operators:

import { useBehaviorSubject } from 'use-observable-hooks';
import { map } from 'rxjs/operators';

function DoubleCounter() {
  const [doubledCount, setCount] = useBehaviorSubject(
    0,
    map((n) => n * 2)
  );

  return (
    <button onClick={() => setCount(doubledCount / 2 + 1)}>
      Doubled Count: {doubledCount}
    </button>
  );
}

useSubject

Use an RxJS Subject to emit and receive values. Unlike BehaviorSubject, a Subject has no initial value.

import { useSubject } from 'use-observable-hooks';

function EventEmitter() {
  const [event, emitEvent, error] = useSubject<string>();

  return (
    <div>
      <p>Last Event: {event ?? 'None'}</p>
      <button onClick={() => emitEvent('Click')}>Emit Click</button>
      <button onClick={() => emitEvent('Hover')}>Emit Hover</button>
    </div>
  );
}

With RxJS operators:

import { useSubject } from 'use-observable-hooks';
import { debounceTime, map } from 'rxjs/operators';

function SearchInput() {
  const [debouncedSearch, setSearch] = useSubject<string>(
    debounceTime(300),
    map((query) => query.toLowerCase())
  );

  return (
    <div>
      <input onChange={(e) => setSearch(e.target.value)} />
      <p>Searching for: {debouncedSearch ?? 'Nothing yet'}</p>
    </div>
  );
}