RxJS Use Hooks

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useObservable ​

Use an RxJS Observable, return a value, and automatically unsubscribe from it when the component is unmounted.

Usage ​

tsx
import { useMemo } from 'react'
import { useObservable } from 'rxjs-use-hooks'
import { interval } from 'rxjs'
import { mapTo, scan, startWith } from 'rxjs/operators'

// Comp()
const obs = useMemo(() => interval(1000).pipe(
  mapTo(1),
  startWith(0),
  scan((total, next) => next + total)
), [])

const count = useObservable(
  obs
)

If you want to add custom error handling to an Observable that might error, you can supply an optional onError configuration. Without this, RxJS will treat any error in the supplied Observable as an "unhandled error" and it will be thrown in a new call stack and reported to window.onerror.

tsx
import { useMemo } from 'react'
import { useObservable } from 'rxjs-use-hooks'
import { interval } from 'rxjs'
import { map } from 'rxjs/operators'

// Comp()
const obs = useMemo(() => interval(1000).pipe(
  map((n) => {
    if (n === 10)
      throw new Error('oops')

    return n + n
  }),
))

const count = useObservable(
  obs,
  {
    onError: (err) => {
      console.log(err.message) // "oops"
    },
  },
)

Type Declarations ​

tsx
import { Observable } from "rxjs";
export interface UseObservableOptions<I> {
    onError?: (err: any) => void;
    /**
     * The value that should be set if the observable has not emitted.
     */
    initialValue?: I | undefined;
}
export declare function useObservable<H, I = undefined>(observable: Observable<H>, options?: UseObservableOptions<I | undefined>): H | I | undefined;