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docs: add destructuring actions with props example for createReducer… #1987

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Jul 9, 2019
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docs: add destructuring actions with props example for createReducer… #1987

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docs: add destructuring actions with props example for createReducer…
Jul 2, 2019
fa30310
docs: add using createReducer with example (#1987)
Jul 2, 2019
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docs: removes using createReducer section and adds destructiong actio…
Jul 9, 2019
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7 changes: 5 additions & 2 deletions projects/ngrx.io/content/guide/store/reducers.md
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ import { createAction } from '@ngrx/store';
export const homeScore = createAction('[Scoreboard Page] Home Score');
export const awayScore = createAction('[Scoreboard Page] Away Score');
export const resetScore = createAction('[Scoreboard Page] Score Reset');
export const setScores = createAction('[Scoreboard Page] Set Scores');

</code-example>

Expand Down Expand Up @@ -72,7 +73,8 @@ const scoreboardReducer = createReducer(
initialState,
on(ScoreboardPageActions.homeScore, state => ({ ...state, home: state.home + 1 })),
on(ScoreboardPageActions.awayScore, state => ({ ...state, away: state.away + 1 })),
on(ScoreboardPageActions.resetScore, state => ({ home: 0, away: 0 }))
on(ScoreboardPageActions.resetScore, state => ({ home: 0, away: 0 })),
on(ScoreboardPageActions.setScores, (state, { game }) => ({ home: game.home, away: game.away }))
);

export function reducer(state: State | undefined, action: Action) {
Expand All @@ -86,7 +88,8 @@ export function reducer(state: State | undefined, action: Action) {

</div>

In the example above, the reducer is handling 3 actions: `[Scoreboard Page] Home Score`, `[Scoreboard Page] Away Score`, and `[Scoreboard Page] Score Reset`. Each action is strongly-typed. Each action handles the state transition immutably. This means that the state transitions are not modifying the original state, but are returning a new state object using the spread operator. The spread syntax copies the properties from the current state into the object, creating a new reference. This ensures that a new state is produced with each change, preserving the purity of the change. This also promotes referential integrity, guaranteeing that the old reference was discarded when a state change occurred.
In the example above, the reducer is handling 4 actions: `[Scoreboard Page] Home Score`, `[Scoreboard Page] Away Score`, `[Scoreboard Page] Score Reset` and `[Scoreboard Page] Set Scores`. Each action is strongly-typed. Each action handles the state transition immutably. This means that the state transitions are not modifying the original state, but are returning a new state object using the spread operator. The spread syntax copies the properties from the current state into the object, creating a new reference. This ensures that a new state is produced with each change, preserving the purity of the change. This also promotes referential integrity, guaranteeing that the old reference was discarded when a state change occurred.


<div class="alert is-important">

Expand Down