obaranovskyi

import { Observable, Subscriber } from 'rxjs';

const obs = new Observable((subscriber: Subscriber<number>) => {
  subscriber.next(1);
  subscriber.complete();
});

obs.subscribe(console.log);

obaranovskyi

import { firstValueFrom, Observable, Subject } from 'rxjs';

async function demo<T>(observable: Observable<T>): Promise<void> {
  const result = await firstValueFrom(observable);

  console.log(result);
}

const subject = new Subject();
const obs = subject.asObservable();

obaranovskyi

import { EmptyError, firstValueFrom, Observable, Subject } from 'rxjs';

async function demo<T>(observable: Observable<T>): Promise<void> {
  try {
    const result = await firstValueFrom(observable);

    console.log(result);
  } catch (error) {
    console.log(error instanceof EmptyError);
    console.error(error);

obaranovskyi

import { firstValueFrom, Observable, Subject } from 'rxjs';

async function demo<T>(observable: Observable<T>): Promise<void> {
  try {
    const result = await firstValueFrom(observable, { defaultValue: 25 });

    console.log(result);
  } catch (error) {
    console.error(error);
  }

obaranovskyi

import { lastValueFrom, Observable, Subject } from 'rxjs';

async function demo<T>(observable: Observable<T>): Promise<void> {
  const result = await lastValueFrom(observable);

  console.log(result);
}

const subject = new Subject();
demo(subject.asObservable());

obaranovskyi

import { EmptyError, lastValueFrom, Observable, Subject } from 'rxjs';

async function demo<T>(observable: Observable<T>): Promise<void> {
  try {
    const promiseResult = await lastValueFrom(observable);

    console.log(promiseResult);
  } catch (error) {
    console.log(error instanceof EmptyError);
    console.error(error);

obaranovskyi

import { EmptyError, lastValueFrom, Observable, Subject } from 'rxjs';

async function demo<T>(observable: Observable<T>): Promise<void> {
  try {
    const promiseResult = await lastValueFrom(observable, { defaultValue: 25 });

    console.log(promiseResult);
  } catch (error) {
    console.log(error instanceof EmptyError);
    console.error(error);

obaranovskyi

import { from } from 'rxjs';

from(Promise.resolve(2))
  .subscribe({
    next: console.log,
    error: console.error,
    complete: () => console.log(`complete`)
  });

obaranovskyi

import {
  combineLatest,
  of,
  merge,
  concat,
  exhaustMap,
  mergeMap,
  concatMap,
  forkJoin,
} from 'rxjs';

obaranovskyi

import { from } from 'rxjs';

const fromPromise$ = from(
  new Promise((resolve, reject) => {
    console.log('Will be invoked only once, and right away.')
    resolve(3);
  })
);