Angular Using Store And Effects

Angular Using Store and Effects Step by step Implementation and Top 10 Questions and Answers

Last Update:6/1/2025 12:00:00 AM .NET School AI Teacher - SELECT ANY TEXT TO EXPLANATION. 25 mins read Difficulty-Level: beginner

Using Store and Effects in Angular with NgRx

In modern web development, managing the state of an application efficiently is critical for scalability and performance. For large-scale Angular applications, NgRx provides a powerful solution that leverages the principles of Reactive Programming and the Redux design pattern to manage application state in a predictable manner. Two main components of NgRx are the Store and Effects, each serving a unique purpose but working in tandem to create a robust and maintainable application state management system.

NgRx Store: Centralized State Management

The Store in NgRx serves as the single source of truth for your application's state. It is a simple key-value store where you can query and update your application state consistently across different parts of your application. The state within the Store is immutable, meaning that it can never be directly modified. Instead, you make changes via actions, which trigger reducers to produce a new state based on the current one.

Important Information:

State Shape: Before building your store, define the shape of your application state. The state should be normalized to avoid redundancy and make it easier to write reducers.
```
interface AppState {
  user: UserState;
  products: ProductState;
}
```
Actions: Actions are payloads of information that send data from your application to your NgRx store. Every action has a type, which describes the event, and often includes a payload containing additional data about the event.
```
export const loadProducts = createAction(
  '[Product Page] Load Products',
  props<{ productId: number }>()
);
```
Reducers: Reducers are pure functions that take the current state and an action as arguments and returns the new state. Reducers determine how the state should change based on actions.
```
const productReducer = createReducer(
  initialState,
  on(loadProductsSuccess, (state, { products }) => ({ ...state, products }))
);
```
Selectors: Selectors are functions that allow you to retrieve slices of state directly from the store. They are essential for extracting necessary data from the central store and minimizing re-renders.
```
export const getUserProfile = createSelector(
  selectUserState,
  (state) => state.profile
);
```
NgRx/Devtools: NgRx DevTools offer a powerful debugging experience by allowing you to inspect every state and action mutation in real-time. This ensures that state mutations are happening as expected and helps in understanding any issues.

NgRx Effects: Handling Side Effects

While NgRx Store is responsible for synchronous state management, NgRx/Effects handle asynchronous operations like HTTP requests, WebSocket communications, or interactions with the browser itself. Effects listen for dispatched actions, perform effects (like calling APIs), and dispatch new actions based on the outcome of those effects. This separation keeps side effects out of your component logic, leading to cleaner and more maintainable code.

Important Information:

Effect Decorator: Effects are decorated with the @Effect decorator (or simply @Injectable in NgRx v8+). They listen to actions and return either a new action or no action at all.

@Injectable()
export class DataEffects {
  constructor(private actions$: Actions, private http: HttpClient) {}

  loadData$ = createEffect(() =>
    this.actions$.pipe(
      ofType(loadData),
      mergeMap(() =>
        this.http.get('/api/data').pipe(
          map(response => loadDataSuccess({ response })),
          catchError(() => of(loadDataFailure()))
        )
      )
    );
  );
}

Actions$: Actions Observable: Actions$ is an observable of all actions that have been dispatched to the Store. It allows Effects to listen for specific actions and react accordingly.
```
this.actions$.pipe(ofType(addProduct))
```
Operators: Common RxJS operators used in Effects include:
- mergeMap: Used to handle multiple HTTP calls simultaneously.
- switchMap: Aborts previous HTTP calls when a new one is started.
- map: Maps the response from the HTTP call to the corresponding action.
- catchError: Handles errors gracefully by dispatching a failure action.

Testing Effects: NgRx Effects come with their own testing utilities which help ensure that your Effects properly listen for actions, perform operations, and dispatch the correct outcomes.

it('should dispatch the loadProductsSuccess action', () => {
  const action = loadProducts();
  const completion = loadProductsSuccess({ products });

  actions$.next(action);

  effects.loadData$.subscribe(result => {
    expect(result).toEqual(completion);
  });
});

Effect Lifecycle: Effects can also be utilized during the lifecycle of a component, such as initialization (ngOnInit) or destruction (ngOnDestroy). This allows you to trigger actions and effects only when necessary.

Integration and Best Practices

Integrating NgRx Store and Effects into an Angular application involves several steps. These steps need to be undertaken carefully to ensure that your state management system remains clean, efficient, and scalable.

Important Information:

Setting Up the Module: Create an NgRx Module using Angular CLI that integrates Store, Effects, Router Store, etc.
```
ng generate module app-state --flat false
```

Providing Store/Effects: Import and provide the NgRx Store and Effects in your main module or wherever they are needed.

import { EffectsModule } from '@ngrx/effects';
import { StoreModule } from '@ngrx/store';
import { StoreDevtoolsModule } from '@ngrx/store-devtools';

@NgModule({
  declarations: [...],
  imports: [
    StoreModule.forRoot(reducers),
    EffectsModule.forRoot([dataEffects]),
    StoreDevtoolsModule.instrument({ maxAge: 25 })
  ]
})
export class AppModule {}

Using Store in Components: Inject the Store service into your components to access and modify the state.

import { Store } from '@ngrx/store';

@Component({...})
export class MyComponent {
  constructor(private readonly store: Store<State>) {}

  fetchProducts() {
    this.store.dispatch(loadProducts());
  }
}

Dispatching Actions: Actions are typically dispatched via services or directly within components.

import { Component, OnInit } from '@angular/core';
import { Store } from '@ngrx/store';
import * as ProductActions from '../actions/products.actions';

@Component({...})
export class ProductListComponent implements OnInit {
  constructor(private store: Store<AppState>) {}

  ngOnInit() {
    this.store.dispatch(ProductActions.loadProducts());
  }
}

Handling State Changes: Use NgRx/Store's select method combined with RxJS operators like async or subscribe to reactively handle state changes.

import { OnInit } from '@angular/core';
import { Store, select } from '@ngrx/store';
import { Observable } from 'rxjs';
import { map, switchMap } from 'rxjs/operators';
import * as fromProduct from '../reducers/product.reducer';
import { Product } from '../models/product.model';

@Component({...})
export class ProductListComponent implements OnInit {
  products$: Observable<Product[]> = this.store.pipe(
    select(fromProduct.selectAllProducts)
  );

  constructor(private store: Store<fromProduct.State>) {}

  ngOnInit(): void {}
}

// In template
<div *ngFor="let product of products$ | async">
  {{ product.name }}
</div>

Feature Modules: Organize your NgRx Store and Effects into feature modules for better modularity and reusability.

@NgModule({
  imports: [
    StoreModule.forFeature('products', productReducer),
    EffectsModule.forFeature([ProductsEffects])
  ],
  declarations: [],
  providers: []
})
export class ProductsModule {}

Avoid Overuse: While Effects are powerful, overusing them can lead to a spaghetti code situation. Only use Effects for side effects; keep synchronous updates within reducers.

By effectively using both the Store and Effects within NgRx, Angular developers can build scalable, efficient applications with a predictable and manageable state. Remember that while NgRx provides a solution, it’s important to understand the underlying principles before fully committing to using it in larger applications. Proper organization, clear definitions, and careful testing will ensure that NgRx enhances rather than complicates your development process.

Understanding Angular Using Store and Effects: A Step-by-Step Guide

When working with large-scale applications, managing state centrally through a predictable and efficient way becomes crucial. The @ngrx/store (NgRx Store) library provides a robust solution for centralized state management, while @ngrx/effects (NgRx Effects) enables you to manage side effects such as fetching data from an API in a clean and organized manner. This guide aims to introduce these concepts with step-by-step examples.

Setting Up Your Angular Environment

Before diving into NgRx Store and Effects, ensure your Angular development environment is set up correctly:

Install Node.js and npm: Download and install Node.js from its official website (https://nodejs.org/).
Install Angular CLI: Open your command line interface (CLI) and run:
```
npm install -g @angular/cli
```
Create a New Angular Project: Use the Angular CLI to generate a new project:
```
ng new angular-store-effects-app
cd angular-store-effects-app
```

Install NgRx Packages

NgRx is a collection of libraries that are built upon each other but can also be used individually. For this guide, we will be using @ngrx/store and @ngrx/effects.

Install NgRx Store:
```
npm install @ngrx/store --save
```
Install NgRx Effects:
```
npm install @ngrx/effects --save
```
Install RxJS (if not installed):
```
npm install rxjs@latest --save
```

Step 1: Set Up the Store

Let's assume we're building an application that needs to fetch user data. To start with, we need to define the store.

Define Interfaces for State

First, create an interface UserState to describe the structure of your state. Place this interface inside a file named user.model.ts in the src/app/models folder.

// src/app/models/user.model.ts

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

export interface UserState {
    users: User[];
    loading: boolean;
    error: string | null;
}

Create Action Types

Next, create action types that define the actions dispatched in your application. Place these constants inside a new file named user.actions.ts in the src/app/store/actions folder.

// src/app/store/actions/user.actions.ts

import { createAction, props } from '@ngrx/store';

export const loadUsers = createAction('[User] Load Users');
export const loadUsersSuccess = createAction('[User] Load Users Success', props<{ users: any[]}>());
export const loadUsersFailure = createAction('[User] Load Users Failure', props<{ error: any}>());

Create Reducer

A reducer takes the current state and an action and returns a new state based on the action type. Create a user.reducer.ts file inside src/app/store/reducers.

// src/app/store/reducers/user.reducer.ts

import { createReducer, on } from '@ngrx/store';
import * as UserActions from '../actions/user.actions';
import { UserState } from '../../models/user.model';

export const initialState: UserState = {
    users: [],
    loading: false,
    error: null,
};

export const userReducer = createReducer(
    initialState,
    on(UserActions.loadUsers, (state) => ({
        ...state,
        loading: true,
        error: null,
    })),
    on(UserActions.loadUsersSuccess, (state, { users }) => ({
        ...state,
        users,
        loading: false,
    })),
    on(UserActions.loadUsersFailure, (state, { error }) => ({
        ...state,
        loading: false,
        error,
    }))
);

Register Reducer with Store Module

Now, register this reducer in AppModule. Import StoreModule.forRoot and pass the configuration object which includes our userReducer.

// src/app/app.module.ts

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { StoreModule } from '@ngrx/store';
import { userReducer } from './store/reducers/user.reducer';

import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    StoreModule.forRoot({ users: userReducer }, {}),
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Step 2: Set Up Effects

Effects are used in NgRx for handling asynchronous operations such as API calls.

Implement Effect

Create an effect to handle the loading of users via an injected service. First, define a service that fetches user data.

// src/app/services/user.service.ts

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';
import { map, catchError } from 'rxjs/operators';
import { of } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class UserService {

  constructor(private http: HttpClient) {}

  getUserData(): Observable<any[]> {
    return this.http.get<any[]>('https://jsonplaceholder.typicode.com/users')
      .pipe(
        map((users: any[]) => users),
        catchError(err => of(err))
      );
  }
}

Next, define an effect inside user.effects.ts to call this service method and dispatch appropriate actions based on the outcome.

// src/app/store/effects/user.effects.ts

import { Injectable } from '@angular/core';
import { Actions, createEffect, ofType } from '@ngrx/effects';
import { exhaustMap, map, catchError } from 'rxjs/operators';
import { of } from 'rxjs';

import * as UserActions from '../actions/user.actions';
import { UserService } from '../../services/user.service';

@Injectable()
export class UserEffects {

  constructor(private actions$: Actions, private userService: UserService) {}

  loadUsers$ = createEffect(() =>
    this.actions$.pipe(
      ofType(UserActions.loadUsers),
      exhaustMap(() =>
        this.userService.getUserData().pipe(
          map(users => UserActions.loadUsersSuccess({ users })),
          catchError(error => of(UserActions.loadUsersFailure({ error })))
        )
      )
    )
  );

}

Import HttpClientModule and EffectsModule

Ensure HttpClientModule is imported in your AppModule, as it is necessary for the HTTP call. Also, import EffectsModule.forRoot to register the effects.

// src/app/app.module.ts

import { HttpClientModule } from '@angular/common/http';
import { EffectsModule } from '@ngrx/effects';
import { UserEffects } from './store/effects/user.effects';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    HttpClientModule,
    StoreModule.forRoot({ users: userReducer }, {}),
    EffectsModule.forRoot([UserEffects]),
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Step 3: Dispatch Actions

In the component where you want to display and fetch user data, inject Store and UserService, then dispatch the actions.

// src/app/components/user-list/user-list.component.ts

import { Component, OnInit } from '@angular/core';
import { Store, select } from '@ngrx/store';
import { Observable } from 'rxjs';

import * as UserActions from '../../store/actions/user.actions';
import { UserState } from '../../models/user.model';
import { UserService } from '../../services/user.service';

@Component({
  selector: 'app-user-list',
  templateUrl: './user-list.component.html',
  styleUrls: ['./user-list.component.css']
})
export class UserListComponent implements OnInit {

  users$: Observable<UserState['users']>;
  loading$: Observable<UserState['loading']>;
  error$: Observable<UserState['error']>;

  constructor(private store: Store<{ users: UserState }>, private userService: UserService) { }

  ngOnInit(): void {
    this.users$ = this.store.pipe(select('users', 'users'));
    this.loading$ = this.store.pipe(select('users', 'loading'));
    this.error$ = this.store.pipe(select('users', 'error'));

    // Dispatch action to load users
    this.store.dispatch(UserActions.loadUsers());
  }
}

Step 4: Data Flow in the Application

The data flow in this example follows the below sequence:

Component Dispatches an Action: Upon initialization, the UserListComponent dispatches the loadUsers action.
Reducer Reacts to the Action: The userReducer receives the action and changes the state to indicate that the loading process has started.
Effects Handle Async Operations: When the reducer picks up the loadUsers action, the UserEffects starts working by calling the getUserData method from UserService.
Service Communicates with Server: The getUserData method sends a GET request to the server.
Data is Received via Service: If the HTTP call succeeds, the service emits the user data to the UserEffects.
Effects Dispatches Another Action: After receiving the data, UserEffects dispatches the loadUsersSuccess action along with the fetched user data.
Reducer Updates State Again: The userReducer receives this new action, updates the state to hold the fetched user data, and indicates that the loading process has completed.

In case the HTTP call fails, the getUserData method will emit an error, and UserEffects will dispatch the loadUsersFailure action along with the error details.

Error Information is Displayed: The UserListComponent subscribes to the error observable, and if an error occurs, it can display an error message to the user.

Through this step-by-step approach, you can effectively understand how Angular with NgRx Store and Effects can manage complex state and side-effect scenarios efficiently. Ensure you follow best practices for organizing reducers, effects, and actions when scaling your application for better maintainability and readability.

Top 10 Questions and Answers: Angular Using Store and Effects

1. What is Angular Store?

Answer: Angular Store (also known as NgRx Store) is a state management library used in Angular applications to manage the application's data at the global level. It serves as a single source of truth for the entire application, enabling efficient and predictable state management, especially for complex applications with a lot of state interactions. NgRx Store is highly inspired by Redux and follows similar principles of one-way state flow. Here’s a brief on how it works:

State: The entire state of your application is stored in an immutable object tree inside a single store.
Reducer: Pure functions that specify how the application's state changes in response to actions sent to the store.
Selectors: Functions that allow you to compute derived state, or values that need to be recomputed based on the current state.
Actions: Plain objects dispatched from components, services, or effects that describe what happened.

2. How do I install and set up NgRx Store in an Angular project?

Answer: To integrate NgRx Store into your Angular project, you need to install the necessary packages and set up the store module. Follow these steps:

Install NgRx Store:

npm install --save @ngrx/store @ngrx/store-devtools

Import StoreModule in the root application module (app.module.ts):

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { StoreModule } from '@ngrx/store';
import { reducers } from './store/reducers'; // import your combined reducers here
import { StoreDevtoolsModule } from '@ngrx/store-devtools';
import { environment } from '../environments/environment';

@NgModule({
  declarations: [
    // ...
  ],
  imports: [
    BrowserModule,
    StoreModule.forRoot(reducers),
    StoreDevtoolsModule.instrument({ maxAge: 25, logOnly: environment.production }),
  ],
  // ...
})
export class AppModule {}

Create reducers, actions, and selectors:

You can use Angular CLI to generate these files using the following commands:

ng generate action books/getBooks --collection=@ngrx/schematics
ng generate reducer Books --collection=@ngrx/schematics
ng generate feature my-feature --reducers=reducers/books --actions=actions/books --collection=@ngrx/schematics

This will structure your application with NgRx conventions, including creating necessary files and folders.

3. What are NgRx Effects and what do they do?

Answer: NgRx Effects is a library for handling side-effects in your Angular application using NgRx Store. Side effects are operations that occur outside of your normal application logic, such as HTTP requests, long-running calculations, or interaction with the browser APIs.

The main function of NgRx Effects is to handle asynchronous tasks, process those tasks without mutating the current state directly, and dispatch actions to the store when necessary. Here’s a brief overview:

Effect: A service that listens for specific actions dispatched to the Store, reacts to them, and performs some sort of operation, like fetching data from a server or processing a value.
Observable: Each effect listens to an Observable, often a Stream of Actions, and performs a reaction to each Action it receives.
Dispatcher: After performing its operation (like a successful GET request), the effect dispatches another action to the Store, reflecting the updated state.

4. How do I create an effect to handle HTTP requests?

Answer: Creating an effect to handle HTTP requests involves several steps. Let’s assume you want to fetch a list of books:

Create an Action:

First, dispatch an action when you want to start fetching data.
```
export const loadBooks = createAction('[Books Page] Book Loaded');
```

Create an Effect:

Then, define an effect that reacts to this action, makes an HTTP request, and dispatches another action based upon the response.

import { Injectable } from '@angular/core';
import { Actions, createEffect, ofType } from '@ngrx/effects';
import { catchError, map, mergeMap } from 'rxjs/operators';
import { of } from 'rxjs';
import { HttpClient } from '@angular/common/http';
import { loadBooksSuccess, loadBooksFailure } from './books.actions';

@Injectable()
export class BooksEffects {
  loadBooks$ = createEffect(() =>
    this.actions$.pipe(
      ofType(loadBooks),
      mergeMap(() => this.http.get('/api/books').pipe(
        map(books => loadBooksSuccess({ books })),
        catchError(error => of(loadBooksFailure({ error }))),
      )),
    );

  constructor(private actions$: Actions, private http: HttpClient) {}
}

Inject the Effect into Your Module:

Make sure the effect is recognized by your application module.

import { NgModule } from '@angular/core';
import { StoreModule } from '@ngrx/store';
import { booksReducer } from './books.reducers'; // import your reducer
import { EffectsModule } from '@ngrx/effects';
import { BooksEffects } from './books.effects'; // import your effect

@NgModule({
  declarations: [
   // ...
  ],
  imports: [
    BrowserModule,
    StoreModule.forRoot({ books: booksReducer }),
    EffectsModule.forRoot([BooksEffects]),
    HttpClientModule,
  ],
})
export class AppModule {}

5. What is the difference between Actions and Reducers in NgRx?

Answer:

Actions: These are plain objects that carry specific information about the type of mutation and the payload of that mutation. Actions are typically dispatched by components or other services via the Store. They describe what happened but not how the state should change in response. For example:
```
export const addBook = createAction('[Book Component] Add Book', prop<{ book: Book }>()); 
```

Reducers: These are pure functions that define how the application's state changes in response to each Action. Reducers take the current state and the Action being dispatched as arguments, return a new state, and perform no mutations to existing state or any other side effects. For example:

import { Book } from '../../book.model';
import { createReducer, on, Action } from '@ngrx/store';
import { addBook, bookAdded } from '../actions/books.action';

export interface State {
  books: Book[];
  loading: boolean;
  loaded: boolean;
  error: Error;
}

export const initialState: AppState = {
  books: [],
  loading: false,
  loaded: false,
  error: undefined,
};

const booksReducer = createReducer(
  initialState,
  on(addBook, (state) => ({ ...state, loading: true })),
  on(bookAdded, (state, { book }) => ({ ...state, books: [...state.books, book], loading: false, loaded: true }))
);

export function reducer(state: State | undefined, action: Action) {
  return booksReducer(state, action);
}

6. How do I listen to changes in the Store and update the UI accordingly?

Answer: When you want to react to state changes and update your component's UI, you subscribe to the Store's state using the select method provided by @ngrx/store. You combine the Store's select method with the async pipe in your component template to keep the UI responsive.

Import Store and select in your component (book-list.component.ts):

import { Component, OnInit } from '@angular/core';
import { Observable } from 'rxjs';
import { Store, select } from '@ngrx/store';
import { Book } from '../../book.model';
import * as fromBooks from '../store/books.reducer';
import * as booksActions from '../store/books.actions';

@Component({
  selector: 'app-book-list',
  templateUrl: './book-list.component.html'
})
export class BookListComponent implements OnInit {
  books$: Observable<Book[]>;

  constructor(private store: Store<fromBooks.State>) {}

  ngOnInit() {
    this.store.dispatch(booksActions.loadBooks());
    this.books$ = this.store.pipe(select(fromBooks.selectBooks));
  }
}

Use the async pipe in your component's template (book-list.component.html):

<ul>
  <li *ngFor="let book of (books$ | async)">
    {{ book.title }}
  </li>
</ul>

Here, the books$ observable is updated whenever the books state in the Store changes, and the UI automatically reflects those changes thanks to the async pipe.

7. Why and how do I use selectors instead of accessing state properties directly?

Answer: Selectors are memoized pieces of code that help you access or extract slices of data from the NgRx Store. They are functions that transform data into a format required by your component.

Using selectors offers several benefits:

Memoization: Selectors are memoized functions, which means they only recalculate their output when one of their input arguments changes. This improves performance by avoiding unnecessary recalculations.
Encapsulation: Selectors encapsulate the access pattern to your state, making your components less dependent on the structure of the overall state tree.
Reusability: Selectors can be reused across different components, improving maintainability.
Derived Data: They enable computation of derived state based on existing state, keeping components focused on presentation.

Here’s how you can create and use a selector:

// books.selectors.ts
import { createSelector, createFeatureSelector } from '@ngrx/store';
import { Book } from '../../book.model';

export interface AppState {
  books: State;
}

export const featureSelector = createFeatureSelector<State>('books');

export const selectBooks = createSelector(
  featureSelector,
  (state: State) => state.books
);

And then use the selector in your component:

// book-list.component.ts
this.books$ = this.store.pipe(select(selectBooks));

8. Can actions with payloads still be handled asynchronously using NgRx Effects?

Answer: Absolutely, actions with payloads can be handled asynchronously using NgRx Effects. When an action is dispatched with a payload, the associated effect can react to it, extract the payload, perform asynchronous operations (such as HTTP requests), and dispatch subsequent actions based on the results.

Here’s how you might do it:

Define an Action with a Payload:

export const createBook = createAction(
  '[Book API] Create Book',
  props<{ createBookRequest: CreateBookRequest }>()
);

Create an Effect to Handle the Action:

@Injectable()
export class BooksEffects {
  createBook$ = createEffect(() =>
    this.actions$.pipe(
      ofType(createBook),
      mergeMap(({ createBookRequest }) =>
        this.apiService.createBook(createBookRequest).pipe(
          map(createdBook => bookCreated({ book: createdBook })),
          catchError(err => of(createBookFailure({ error: err.message })))
        )
      )
    );

  constructor(
    private actions$: Actions,
    private apiService: ApiService,
  ) {}
}

In the above example, when createBook action is dispatched, the createBook$ effect extracts createBookRequest from the action payload, calls an API service to create the book, and dispatches either bookCreated action with a created book object or createBookFailure action with an error message.

9. How does NgRx DevTools help in debugging NgRx applications?

Answer: NgRx DevTools extend functionality provided by NgRx Store to facilitate easier debugging and monitoring of your application's state transformations over time. Here's how:

Time-travel Debugging: You can undo recent actions to see what the previous states were. This helps in identifying bugs related to specific actions.
Action Logging: All dispatched Actions are logged along with the current and next states. This allows you to trace every change in the application.
State Snapshots: You can view state snapshots at any point in history, and compare those with the current state.
Performance Monitoring: The dev tools also have performance monitoring features that help identify slow effects and reducers.

NgRx DevTools integrates seamlessly with Chrome DevTools, providing an intuitive user interface for browsing through your application's state history and interacting with Actions.

10. What are best practices while using NgRx Store and Effects?

Answer: While working with NgRx Store and Effects, it’s important to follow certain best practices to make your state management scalable and maintainable:

Keep reducers pure: Since reducers affect the application's state directly, they must remain free of side effects. Always make sure to return a new state instance instead of modifying the existing one.
Use Actions consistently: Define all necessary actions upfront and document them well. This ensures that all state-related tasks are centralized and easier to audit.
Decouple effects: Avoid mixing business logic with effects. Effects should focus solely on reacting to actions, performing side effects, and dispatching actions.
Leverage memoization: Use selectors effectively to avoid unnecessary recalculations. Take advantage of the built-in memoization capabilities of selectors.
Combine streams: Use RxJS operators like withLatestFrom, mergeMap, concatMap, and exhaustMap to manipulate and combine Observables when needed.
Error Handling: Centralize error handling within effects or within reducers where applicable to keep components clean from error handling concerns.
Lazy Loading Modules: Use feature modules with StoreModule.forFeature() instead of StoreModule.forRoot() for lazy-loaded parts of your app. This keeps your root Store module free of feature-specific logic.
Environment Config: Enable Store DevTools in development only by using environment configurations (logOnly: environment.production). In production, it might impact the app performance unnecessarily.
Testing: Write tests for actions, effects, reducers, and selectors separately. This makes it easy to debug and validate individual pieces of state management logic.
Documentation & Typing: Keep your codebase well-documented (using JSDoc or TypeScript comments) and utilize TypeScript to enforce type-checking at compile-time. This avoids many common errors that can arise from dynamic type changes.

By following these best practices, you can maximize the benefits of using NgRx Store and Effects, enabling a more robust, scalable, and maintainable Angular state management solution.