alex-okrushko

@Effect()
addCartItem: Observable<Action> = this.actions$.pipe(
  ofType<cartActions.AddItem>(cartActions.ADD_ITEM),
  concatMap(({ itemId }) =>
    this.cartService.addToCart(itemId).pipe(
      // Notice, that nothing is passed to the Success.
      map(() => new cartActions.AddItemSuccess()),
      // passing the itemId to the Error, so it can be restored.
      catchError(() => of(new cartActions.AddItemError(itemId)))
    )

alex-okrushko

export function productSync(reducer: ActionReducer<{ product: ProductState }>) {
  return (state, action) => {
    let reducedState = reducer(state, action);
    if (action.type === INIT) {
      const data = window.localStorage.getItem('productData');
      if (data) {
        reducedState = {
          ...reducedState,
          product: JSON.parse(data),
        };

alex-okrushko

export function reducer(
  state: ProductState = initState,
  action: actions.All
): ProductState {
  switch (action.type) {
    ...
    case actions.FETCH_PRODUCTS_SUCCESS: {
      return {
        // addAll replaces current list of products with new list
        products: productAdapter.addAll(action.payload, state.products),

alex-okrushko

@Effect()
  fetchProduct: Observable<Action> = this.actions$.pipe(
    ofType(actions.FETCH_CURRENT_PRODUCT),
    withLatestFrom(
      this.store.select(selectors.getCurrentProductId)
    ),
    switchMap(id =>
      this.productService.getProduct(id).pipe(
        map(product => new actions.FetchProductSuccess(product)),
        catchError(() => of(new actions.FetchProductError()))

alex-okrushko

@Component({...})
export class ProductDetailsComponent {
  product$ = this.store.select(selectors.getCurrentProduct);

  constructor(
    private readonly store: Store<{}>,
  ) {
    this.store.dispatch(new actions.FetchCurrentProduct());
  }
}

alex-okrushko

@Effect()
fetchProducts: Observable<Action> = this.actions$.pipe(
  ofType<actions.FetchProducts>(actions.FETCH_PRODUCTS),
  switchMap(() =>
    this.productService.getProducts().pipe(
      map(products => new actions.FetchProductsSuccess(products)),
      catchError(() => of(new actions.FetchProductsError()))
    )
  )
);

alex-okrushko

it("should handle a basic source that emits next then errors, count=3", () => {
    testScheduler.run(({ expectObservable, cold, expectSubscriptions }) => {
      const source = cold("--1-2-3-#");
      const subs = [      "^       !                ",
                          "        ^        !        ",
                          "                 ^         !"
      ];
      const expected =   "--1-2-3----1-2-3-----1-2-3-#";

      expectObservable(

alex-okrushko

message$ = of('Call me!').pipe(
    switchMap(() => this.service.callBackend()),
    retryBackoff({
        initialInterval: 100, 
        maxRetries: 12,
    }),
);

alex-okrushko

function calculateDelay(iteration, initialInterval) {
 return Math.pow(2, iteration) * initialInterval;
}

alex-okrushko

message$ = of('Call me!').pipe(
    switchMap(() => this.service.callBackend()),
    retryBackoff(1000),
);