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

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data = produce(INITIAL_DATA, draft => {
  draft.items[NEW_ITEM_ID] = { id: NEW_ITEM_ID, name: 'ITEM-NEW', value: 0 }
  draft.counter++
  draft.keys.push(NEW_ITEM_ID)
})

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data = compose(
    over(lensPath(["keys"]), append(NEW_ITEM_ID)),
    over(lensPath(["count"]), x => x + 1),
    set(lensPath(["items", NEW_ITEM_ID]), {
      id: NEW_ITEM_ID,
      name: "ITEM-NEW",
      value: 0
    })
)(INITIAL_DATA);

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data = {
  ...INITIAL_DATA,
  items: {
  	...INITIAL_DATA.items,
  	[NEW_ITEM_ID]: { id: NEW_ITEM_ID, name: 'ITEM-NEW', value: 0 }
  },
  count: INITIAL_DATA.count +1,
  keys: [ ...INITIAL_DATA.keys, NEW_ITEM_ID]
}

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

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

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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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@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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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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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(){},