imkrish

import { Component, OnDestroy, OnInit } from '@angular/core';
import { Observable, Subscription } from 'rxjs';

export class RxJSUtil {
  static unsubscribe = (subscriptions: Subscription[]) =>
    subscriptions.forEach(subscription => subscription.unsubscribe());
}

@Component({
  selector: 'nx-tutorial-root',

imkrish

type DeepReadonlyObject<T> = { readonly [K in keyof T]: DeepReadonly<T[K]> };

type DeepReadonly<T> = T extends (infer E)[][]
  ? ReadonlyArray<ReadonlyArray<DeepReadonlyObject<E>>>
  : T extends (infer E)[]
  ? ReadonlyArray<DeepReadonlyObject<E>>
  : T extends object
  ? DeepReadonlyObject<T>
  : T;

imkrish

interface User {
  readonly id: number;
  readonly name: string;
  readonly wifeName: string;
  readonly parents: ReadonlyArray<string>;
}

const user: User = {
  id: 1,
  name: "John",

imkrish

const numbers: ReadonlyArray<number> = [1, 2, 3, 4, 5];
numbers.push(6); // Property 'push' does not exist on type 'ReadonlyArray<number>'

imkrish

const numbers: number[] = [1, 2, 3, 4, 5];
numbers.push(6); // There is nothing wrong with this

imkrish

interface User {
  readonly id: number;
  name: string;
}

const user: User = {
  id: 1,
  name: "Keerati"
};

imkrish

interface User {
  id: number;
  name: string;
}

const user: User = {
  id: 1,
  name: "Keerati"
};

imkrish

const iAmAwesome = true;
iAmAwesome = false; // Cannot assign to 'iAmAwesome' because it is a constant

imkrish

const observable = of('response')

function hasValue(value: any) {
  return value !== null && value !== undefined;
}

function getValue<T>(observable: Observable<T>): Promise<T> {
  return observable
    .pipe(
      filter(hasValue),

imkrish

const observable = of('response')

const result = await getValue(observable)
// Do the logic with the result
// .................
// .................
// .................