dpalita

const square = (operand: number): number =>  operand * operand
const four = square(2)

dpalita

const fetchNews = (subject: string): Promise<News[]> => {
    return fetch('http://newsApi?subject=' + subject)
              // promise
              .then(res => res.text() /* re promise ^^ */)
}
const trumpNews = fetchNews('Trump')
const kimNews = fetchNews('Kim Jong-Un')
trumpNews.then(news => readNewsAndLaugh(news))
kimNews.then(news => readNewsAndLaugh(news))
Promise.all(trumpNews, kimNews)

dpalita

const observableOfOddSquares =
// observable source
Observable.of(
   // stream d'entier
   1, 2, 3, 4, 5, 6
)
// observer du stream d'entier, observable d'impairs
.filter(num => num % 2)
// observer du stream d'impairs, observable de carrés d'impairs
.map(odd => odd * odd)

dpalita

const bitcoinQuotePromise = fetchQuoteAsPromise('btc') // la requête est émise ici
bitcoinQuotePromise.then(news => buy())
bitcoinQuotePromise.then(news => tweet())
// une seule requête http a été émise

const bitcoinQuoteObservable = fetchQuoteAsObservable('btc') // rien
bitcoinQuoteObservable.subscribe(news => buy()) // la requête est émise ici
bitcoinQuoteObservable.subscribe(news => tweet()) // une autre requête est émise ici
// deux requêtes ont été émises

dpalita

function handleNotifications () {
   const notifications = getNotifications() // as Notification[]
   log(notifications)
   displayNotificationCounter(notifications.length)
   updateNotificationPanel(notifications)
   ...
}
// vs différents blocs indépendants du moment que l'observable de notifications est accessible
const notifications$ = getNotifications() // as Observable<Notification[]>
notifications$.subscribe(notifs => log(notifs))

dpalita

export function accountReducerBootstrapFactory(reducer: AccountReducer) {
  // bootstrap() returns a Promise
  return () => reducer.bootstrap()
}

@NgModule({
...
  providers: [
    {
      provide: APP_INITIALIZER,

dpalita

@Injectable()
export class AccountReducer {
  private initialState: AccountState
...
  bootstrap(): Promise<AccountState> {
    return new Promise(resolve =>
      // rehydrate uses indexedDb to read the state
      this.rehydrate(this.storage).subscribe(initialState => {
        this.initialState = initialState
        resolve()

dpalita

@Injectable()
export class AccountReducer {
  private initialState: AccountState
...
  bootstrap(): Promise<AccountState> {
    return new Promise(resolve =>
      // rehydrate uses indexedDb to read the state
      this.rehydrate(this.storage).subscribe(initialState => {
        this.initialState = initialState
        resolve()

dpalita

@NgModule({
...
})
export class AppModule {
  constructor(applicationInitStatus: ApplicationInitStatus,
              store: Store<AppState>) {
    // dispatch the app init action when all stores have add a chance to rehydrate from indexedDb
    applicationInitStatus.donePromise.then(() => store.dispatch(new AppInitAction()))
  }
}

dpalita

@Injectable()
export class AccountReducer extends EntityReducer<Account> {
  private initialState: AccountState
  
  createReducer() {
    return (state: AccountState, action: Action) => {
      if (action instanceof AppInitAction && state === undefined) {
        return initialState
      } else {
        ...