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// npm install tslint-immutable --save-dev
// tslint.json
{
  "extends": ["tslint-immutable"],
  "rules": {

    // Recommended built-in rules
    "no-var-keyword": true,
    "no-parameter-reassignment": true,
    "typedef": [true, "call-signature"],

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const obj = {
  a: 1,
  b: 2,
  c: {
    d: 3
  }
};

obj.newField = 5;   // You can assign new field

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export type Immutable<T> = T extends (infer R)[]
  ? ImmutableArray<R>
  : T extends Function
  ? T
  : T extends object
  ? ImmutableObject<T>
  : T;

interface ImmutableArray<T> extends ReadonlyArray<Immutable<T>> {}

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function deepCopy(obj) {
 return JSON.parse(JSON.stringify(obj)); // serialize -> deserialize -> unique clone
}

const animals = {
  zebra: {
    food: ['leaves', 'bark'],
    name: 'zebra'
  },
  panda: {

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function deepCopy(obj) {
 return JSON.parse(JSON.stringify(obj)); // serialize -> deserialize -> unique clone
}

const original = { 
   a: undefined, 
   b: { c: undefined }, 
   d: () => undefined 
};

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function deepCopy(obj) {
 return JSON.parse(JSON.stringify(obj)); // serialize -> deserialize -> unique clone
}

const original = {
  a: new Date(),
  b: NaN,
  c: new Function(),
  d: undefined,
  e: function(){},

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function deepCopy(obj) {
 return JSON.parse(JSON.stringify(obj)); // serialize -> deserialize -> unique clone
}

function copy(obj) {
   let clone = Array.isArray(obj) ? [] : {};

   for (let key in obj) {
       let value = obj[key];
       clone[key] = (typeof value === "object") ? copy(value) : value;

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@Component({
  selector: 'my-app',
  template: `
    <b>default</b>: {{ todos$ | async | json }} <br>
    <b>immutable reverse</b>: {{ todosReverse$ | async | json }}
  `
})
export class AppComponent implements OnInit {

  @Select(AppState) 

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import { State, Selector, StateContext, Action } from '@ngxs/store';
import { ImmutableSelector, ImmutableContext } from '@ngxs-labs/immer-adapter';

export class Add {
  static type = 'Add'
  constructor(public payload: number) {}
}

@State<number[]>({
  name: 'todos',

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@State<AnimalsStateModel>({
  name: 'animals',
  defaults: {
    zebra: {
      food: ['leaves', 'bark'],
      name: 'zebra'
    },
    panda: {
      food: [],
      name: 'panda'