isObservable

Checks if a value is an RxJS Observable or any compatible observable.

Uses duck-typing: returns true for any object with both .subscribe() and .pipe() methods, covering Observable, Subject, BehaviorSubject, ReplaySubject, and any RxJS-compatible observable implementation.

Available since v2.0.3

Import

import { isObservable } from '@helpers4/observable';

Signature

isObservable(value: unknown): value is Observable<unknown>

Parameters

Parameter	Type	Description
value	unknown	The value to check

Returns

value is Observable<unknown> — true if value is observable-like

Examples

Detect an RxJS Observable or Subject

Returns true for Observable, Subject, BehaviorSubject, and any duck-typed observable.

import { Observable, Subject } from 'rxjs';
isObservable(new Observable())  // => true
isObservable(new Subject())     // => true
isObservable(Promise.resolve()) // => false
isObservable({})                // => false

Accept either an Observable or a plain value

Use as a guard to normalize inputs that may be Observables or raw values.

import { Observable, of } from 'rxjs';
function toObservable<T>(value: T | Observable<T>): Observable<T> {
  return isObservable(value) ? value : of(value);
}

Source

View source on GitHub