RxJS Typing

Observable with Generics

import { Observable } from 'rxjs';

function numbers(): Observable<number> {
  return new Observable<number>(subscriber => {
    let i = 0;
    const id = setInterval(() => subscriber.next(i++), 1000);
    return () => clearInterval(id);
  });
}

Operators typing

import { map, filter } from 'rxjs/operators';

numbers()
  .pipe(
    filter(n => n % 2 === 0),
    map(n => `Even: ${n}`)
  )
  .subscribe(console.log);

Subject as a typed event bus

import { Subject } from 'rxjs';

type Message = { type: 'info' | 'error'; payload: string };
const bus = new Subject<Message>();
bus.next({ type: 'info', payload: 'hello' });