Mastering Angular Best Practices: Tips and Tricks for Building Large-Scale Applications

Introduction

In this blog post, we'll explore some essential Angular Best Practices for senior and new developers. Let's jump right into the list.

What is Angular?

Angular is a popular framework for building modern web applications. It's known for its robust features, performance, and scalability. However, when working on large-scale projects, following best practices to ensure code maintainability, performance, and scalability is essential. This blog will discuss some Angular best practices for large-scale projects and provide examples of code snippets.

Use a Modular Architecture

A modular architecture in Angular means breaking your application into smaller, reusable pieces. This approach helps to keep your code organized, maintainable, and testable. Angular provides several built-in features to support modular architecture, such as Modules, Components, and Services.

For example, let's say you have a user management feature in your application. You can create a separate module containing its components, services, and other required files for this feature.

// user-management.module.ts

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';

import { UserListComponent } from './user-list/user-list.component';
import { UserService } from './user.service';

@NgModule({
  declarations: [
    UserListComponent
  ],
  imports: [
    CommonModule
  ],
  providers: [
    UserService
  ],
  exports: [
    UserListComponent
  ]
})
export class UserManagementModule { }

Use Lazy Loading

Lazy loading is a technique used to load specific features of an application only when they are needed. This approach helps to improve application performance and reduce the initial load time. In Angular, you can use the loadChildren property in the route configuration to implement lazy loading.

// app-routing.module.ts

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';

const routes: Routes = [
  { path: 'dashboard', loadChildren: () => import('./dashboard/dashboard.module').then(m => m.DashboardModule) },
  { path: 'user-management', loadChildren: () => import('./user-management/user-management.module').then(m => m.UserManagementModule) },
  { path: '', redirectTo: '/dashboard', pathMatch: 'full' },
  { path: '**', redirectTo: '/dashboard' }
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }

Use Reactive Forms

Reactive Forms is a technique used to handle form input in Angular applications. This approach provides a more structured way to manage form data and validation. Reactive Forms are ideal for large-scale applications that require complex form input.

// user-form.component.ts

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';

@Component({
  selector: 'app-user-form',
  templateUrl: './user-form.component.html',
  styleUrls: ['./user-form.component.scss']
})
export class UserFormComponent implements OnInit {
  userForm: FormGroup;

  constructor(private fb: FormBuilder) { }

  ngOnInit(): void {
    this.userForm = this.fb.group({
      name: ['', Validators.required],
      email: ['', [Validators.required, Validators.email]],
      password: ['', Validators.required],
      confirmPassword: ['', Validators.required]
    });
  }

  onSubmit(): void {
    console.log(this.userForm.value);
  }
}

Use Interceptors

Interceptors are a powerful feature in Angular that allow you to intercept HTTP requests and responses. Interceptors are ideal for large-scale applications that make many HTTP requests. This approach helps to centralize error handling, caching, and other common HTTP-related tasks.

// auth.interceptor.ts

import { Injectable } from '@angular/core';
import { HttpInterceptor, HttpRequest, HttpHandler, HttpEvent } from '@angular/common/http';
import { Observable }
import { AuthService } from './auth.service';

@Injectable()
export class AuthInterceptor implements HttpInterceptor {
	constructor(private authService: AuthService) {}

	intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
		const token = this.authService.getToken();
		const authRequest = request.clone({
			headers: request.headers.set('Authorization', Bearer ${token})
		});
		return next.handle(authRequest);
	}
}

Use Angular CLI

The Angular CLI (Command Line Interface) is a powerful tool that simplifies the development process of Angular applications. The CLI provides several built-in features, such as generating components, services, modules, etc. It also provides a built-in development server, testing framework, and build tools.

// Generating a new component using Angular CLI

ng generate component user-list --module=user-management.module.ts

Use TrackBy Function in ngFor Directive

When working with lists in Angular, it's best practice to use the trackBy function in the ngFor Directive. This function helps Angular track list changes and optimize the rendering process.

// Example of using trackBy function in ngFor directive

<div *ngFor="let user of users; trackBy: trackByFn">{{ user.name }}</div>

trackByFn(index, user) {
  return user.id;
}

Use Dependency Injection

Dependency Injection is a powerful feature in Angular that helps to manage application dependencies and make code more modular and testable. It's best practice to use Dependency Injection to inject services into components and other services.

// Example of using Dependency Injection

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';

@Injectable()
export class UserService {
  constructor(private http: HttpClient) {}

  getUsers() {
    return this.http.get('/api/users');
  }
}

Use Pipes for Formatting Data

Pipes are a powerful feature in Angular that helps to format data in templates. It's best practice to use pipes to format data instead of doing it in the component or service.

// Example of using Pipes for formatting data

<div>{{ user.createdAt | date:'dd/MM/yyyy' }}</div>

Use Change Detection Strategy

Angular has two change detection strategies: OnPush and Default. It's best practice to use the OnPush change detection strategy for better performance. This strategy only checks for changes in the @Input properties and not the entire component tree.

// Example of using OnPush change detection strategy

import { Component, Input, ChangeDetectionStrategy } from '@angular/core';

@Component({
  selector: 'app-user',
  templateUrl: './user.component.html',
  styleUrls: ['./user.component.scss'],
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class UserComponent {
  @Input() user: User;
}

Use AOT Compilation

Ahead-of-Time (AOT) compilation is a technique that compiles your Angular application at build time instead of runtime. This can significantly improve your application's performance by reducing the bundle size and eliminating the need for just-in-time (JIT) compilation.

// Example of using AOT compilation

ng build --prod --aot

Use RxJS Operators

RxJS is a powerful library for reactive programming in Angular. It's best practice to use RxJS operators to manipulate data streams instead of doing it in the component or service.

// Example of using RxJS Operators

import { Component } from '@angular/core';
import { UserService } from './user.service';
import { filter, map } from 'rxjs/operators';

@Component({
  selector: 'app-user-list',
  template: `
    <div *ngFor="let user of users$ | async">{{ user.name }}</div>
  `
})
export class UserListComponent {
  users$ = this.userService.getUsers().pipe(
    filter(users => users.length > 0),
    map(users => users.filter(user => user.isActive))
  );

  constructor(private userService: UserService) {}
}

Use NgZone

NgZone is an Angular service that helps manage the change detection process. It's best practice to use NgZone to run code outside the Angular zone for better performance.

// Example of using NgZone

import { Component, NgZone } from '@angular/core';

@Component({
  selector: 'app-root',
  template: `
    <button (click)="runOutsideAngular()">Run Outside Angular</button>
  `
})
export class AppComponent {
  constructor(private ngZone: NgZone) {}

  runOutsideAngular() {
    this.ngZone.runOutsideAngular(() => {
      // Run code outside of the Angular zone
    });
  }
}

Use NgRx for State Management

NgRx is a powerful library for state management in Angular. It's best practice to use NgRx to manage the state of your application for better scalability and maintainability.

// Example of using NgRx for State Management

// Define a state interface
export interface AppState {
  user: User;
}

// Define actions
export const setUser = createAction('[User] Set User', props<{ user: User }>());

// Define a reducer
const initialState: AppState = {
  user: null
};

const appReducer = createReducer(
  initialState,
  on(setUser, (state, { user }) => ({ ...state, user }))
);

// Define a store
@NgModule({
  imports: [
    StoreModule.forRoot({ app: appReducer })
  ]
})
export class AppModule {}

// Use the store in a component
import { Component } from '@angular/core';
import { Store } from '@ngrx/store';
import { setUser } from './app.actions';

@Component({
  selector: 'app-root',
  template: `
    <div *ngIf="user$ | async as user">{{ user.name }}</div>
  `
})
export class AppComponent {
  user$ = this.store.select(state => state.app.user);

  constructor(private store: Store) {}

  ngOnInit() {
    this.store.dispatch(setUser({ user: { name: 'John Doe' } }));
  }
}

Use Angular Material for UI Components

// Example of using Angular Material for UI Components

import { NgModule } from '@angular/core';
import { MatButtonModule } from '@angular/material/button';
import { MatIconModule } from '@angular/material/icon';

@NgModule({
  imports: [
    MatButtonModule,
    MatIconModule
  ],
  exports: [
    MatButtonModule,
    MatIconModule
  ]
})
export class MaterialModule {}

// Use the Material module in a component
import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  template: `
    <button mat-button>
      <mat-icon>menu</mat-icon>
      Open Menu
    </button>
  `
})
export class AppComponent {}

Conclusion

These Angular best practices will help you build a high-performance, maintainable, scalable application. Keeping your code organized and consistent will make it easier for yourself and others to understand and maintain your codebase.

So, always keep these best practices in mind when developing large-scale applications with Angular. 

Happy Coding!!