Examples for https://medium.com/p/651f4b7d45cf/edit

1-example.js

// An observable that emits 10 multiples of 100 every 1 second
const source$ = Observable.interval(1000)
  .take(10)
  .map(x => x * 100);
/**
 * returns a promise that waits `ms` milliseconds and emits "done"
 */
function promiseDelay(ms) {
  return new Promise(resolve => {
    setTimeout(() => resolve('done'), ms);
  });
}

// using it in a switchMap
source$.switchMap(x => promiseDelay(x)) // works
  .subscribe(x => console.log(x)); 

source$.switchMap(promiseDelay) // just a little more terse
  .subscribe(x => console.log(x)); 

// or takeUntil
source$.takeUntil(doAsyncThing('hi')) // totally works
  .subscribe(x => console.log(x))

// or weird stuff you want to do like
Observable.of(promiseDelay(100), promiseDelay(10000)).mergeAll()
  .subscribe(x => console.log(x))

2-example.js

function getErroringPromise() {
  console.log('getErroringPromise called');
  return Promise.reject(new Error('sad'));
}

Observable.defer(getErroringPromise)
  .retry(3)
  .subscribe(x => console.log);

// logs "getErroringPromise called" 4 times (once + 3 retries), then errors

3-example.js

Observable.defer(async function() {
  const a = await Promise.resolve(1);
  const b = a + await Promise.resolve(2);
  return a + b + await Promise.resolve(3);
})
.subscribe(x => console.log(x)) // logs "7"

4-example.js

const button = document.querySelector('button');
const click$ = Observable.fromEvent(button, 'click');

/**
 * Waits for 10 clicks of the button
 * then posts a timestamp of the tenth click to an endpoint
 * using fetch
 */
async function doWork() {
  await click$.take(10)
    .map((_, i) => i + 1)
    .forEach(n => console.log(`click ${n}`));
  return await fetch(
    'notify/tenclicks',
    { method: 'POST', body: Date.now() }
  );
}

doWork();

5-example.js

const source$ = Observable.interval(1000).take(3); // emits 0, 1, 2

// waits 3 seconds, then logs "2".
// because the observable takes 3 seconds to complete, and 
// the interval emits incremented numbers starting at 0
async function test() {
  console.log(await source$.toPromise());
}

test();