Best Practices That You Need To Follow For Building Scalable Angular Applications

11 min readApr 7, 2023

Angular is a popular open-source JavaScript framework for building client-side web applications. An Angular application is a web application built using the Angular framework. It follows the Model-View-Controller (MVC) architectural pattern and comprises components, services, directives, templates, and modules.

A scalable Angular application is developed using the Angular framework that can easily accommodate growth in terms of features, users, and data without experiencing a significant reduction in performance or functionality.

You can efficiently scale your Angular applications through various techniques such as code optimization, efficient use of components, services, and modules, use of lazy loading, and code splitting.

By implementing these techniques, developers can ensure that their Angular application can handle increasing numbers of users and data while still delivering an excellent user experience.

Here are some best practices for building scalable Angular applications:

Use Lazy Loading

Lazy loading is the process of loading a module or component only when it is required rather than loading the entire application at once. This improves the application’s loading time and makes it more scalable.

Lazy loading is a technique used in Angular applications to improve performance by loading modules and components only when needed. Here are some best practices for using lazy loading in Angular:

Plan your application structure: Before implementing lazy loading, plan your application structure and break it into smaller modules. Identify which modules are not critical to the initial load time and can be loaded later when needed.
Use the Angular CLI to generate lazy-loaded modules: The Angular CLI provides a command to generate a module with lazy-loading support. This command will generate a module with a separate routing module and a module file that can be loaded on demand.
Use loadChildren in routing: To load a module lazily, use the loadChildren property in the routing configuration. The value of loadChildren is a string that points to the module file to load.
Use preloadingStrategy: To improve the user experience, consider using a preloading strategy. A preloading strategy loads all lazy-loaded modules in the background, so when the user navigates to a lazy-loaded route, the module is already loaded. Use the
PreloadAllModules strategy to preload all the modules.
Use the RouterLink directive: To ensure that the router knows which routes are lazy-loaded, use the RouterLink directive to navigate to lazy-loaded routes.
Keep lazy-loaded modules small: Lazy-loaded modules should be kept small and focused on a specific feature. If a module becomes too large, consider breaking it into smaller modules.
Test your lazy-loaded modules: Ensure that all your lazy-loaded modules are working as expected by testing them thoroughly. Use tools like the Angular CLI to run tests on lazy-loaded modules.

By following these best practices, you can effectively use lazy loading to improve the performance of your Angular application.

Use RxJS

RxJS is a library that enables reactive programming in Angular applications. It provides a way to manage and manipulate data streams in a scalable and efficient manner.

RxJS is a powerful reactive programming library that can be used in Angular applications to handle asynchronous data streams.

Let me help you by summarizing the essential steps to use RxJS in your Angular application.

Import the RxJS library
Create an Observable
Subscribe to the Observable
Use RxJS operator

Here are the steps in detail that will help you to use RxJS in an Angular application:

Import the RxJS library: To use RxJS in your Angular application, you first need to import the library. You can do this by adding the following line to your component or module file:

import { Observable } from ‘rxjs’;

This imports the Observable class from the RxJS library.

Create an Observable: Once you have imported the Observable class, you can create an Observable by calling the Observable.create() method. This method takes a function as an argument that defines how the Observable will emit data over time.

const myObservable = new Observable(observer => {
   // Emit data over time using the observer object
});

Subscribe to the Observable: To consume the data emitted by an Observable, you need to subscribe to it. You can do this by calling the subscribe() method on the Observable instance.

myObservable.subscribe(data => {
   // Do something with the data emitted by the Observable
});

Use RxJS operators: RxJS provides a wide range of operators that can be used to transform, filter, or combine data emitted by an Observable. You can use operators such as map(), filter(), and combineLatest() to process the data emitted by an Observable.

myObservable.pipe(
   filter(data => data > 0),
   map(data => data * 2)
).subscribe(transformedData => {
   // Do something with the transformed data
});

By following these steps, you can effectively use RxJS in your Angular application to handle asynchronous data streams and create reactive and scalable code.

Use OnPush Change Detection

By using the OnPush change detection strategy, you can improve the performance of your application by reducing the number of times Angular checks for changes. This is because OnPush only triggers a change detection when the inputs of a component change.

Angular provides several change detection strategies to update the view when data changes.

One of the most efficient strategies is the OnPush change detection strategy, which updates the view only when the input properties of a component or directive change or when an event is triggered.

Here, I am highlighting easy steps to use the OnPush change detection method in an Angular application.

Set the change detection strategy
Use immutable objects
Use the async pipe
Use ngOnChanges()

Here are the detailed steps to use the OnPush change detection strategy in an Angular application:

Set the change detection strategy: To use the OnPush change detection strategy, you need to set the change detection strategy of your component or directive to OnPush. You can do this by adding the following line to your component or directive file:

@Component({
   selector: 'my-component',
   templateUrl: './my-component.component.html',
   changeDetection: ChangeDetectionStrategy.OnPush
})

This sets the change detection strategy of your component or directive to OnPush.

Use immutable objects: OnPush change detection strategy works best with immutable objects, which are objects that cannot be modified once created. You can use libraries such as Immutable.js or Immer.js to create immutable objects.

Use the async pipe: The async pipe is a built-in Angular pipe that works well with the OnPush change detection strategy. Use the async pipe to handle asynchronous data streams and update the view when the data changes.

Use ngOnChanges(): OnPush change detection strategy only updates the view when the input properties of a component or directive change. To detect changes in input properties, you can use the ngOnChanges() lifecycle hook. This hook is called whenever an input property changes, and you can use it to trigger changes in the component or directive.

export class MyComponent implements OnChanges {
   @Input() myData: any;

   ngOnChanges(changes: SimpleChanges) {
      // Do something when myData changes
   }
}

By following these steps, you can effectively use the OnPush change detection strategy in your Angular application to improve performance and reduce unnecessary view updates.

Use Angular Universal

Angular Universal is a server-side rendering engine that can help improve the performance and scalability of your application by pre-rendering the content on the server.

Angular Universal is a server-side rendering solution for Angular applications that allows your application to be rendered on the server before being sent to the client.

This can improve performance, SEO, and the user experience by reducing the initial load time and ensuring that search engine bots can easily crawl and index your application.

Key steps to implementing Angular Universal in Angular application.

Install the necessary dependencies
Create a server module
Update your main.ts file
Update your app.component.html file
Update your app.module.ts file

Here are the steps to implement Angular Universal in your Angular application:

Install the necessary dependencies: To use Angular Universal, you need to install the @angular/platform-server and @nguniversal/express-engine packages. You can do this by running the following command:

npm install @angular/platform-server @nguniversal/express-engine — save

Create a server module: To create a server module, you need to create a new file named app.server.module.ts in your application’s root directory. This module will be used to bootstrap your application on the server.

import { NgModule } from '@angular/core';
import { ServerModule } from '@angular/platform-server';
import { AppModule } from './app.module';
import { AppComponent } from './app.component';

@NgModule({
   imports: [
      ServerModule,
      AppModule
   ],
   bootstrap: [AppComponent]
})
export class AppServerModule {}

Update your main.ts file: In your main.ts file, you need to import and use the renderModuleFactory() function to render your application on the server.

import { enableProdMode } from '@angular/core';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { renderModuleFactory } from '@angular/platform-server';
import { AppServerModule } from './app.server.module';
import { environment } from './environments/environment';

if (environment.production) {
   enableProdMode();
}

document.addEventListener('DOMContentLoaded', () => {
   const factory = AppServerModuleNgFactory.create(AppServerModule);
   renderModuleFactory(factory, {
      document: document,
      url: '/'
   }).then(() => {
      // The application has been rendered on the server
   });
});

Update your app.component.html file: You need to replace your <app-root> tag with the <router-outlet> tag in your app.component.html file.

<router-outlet></router-outlet>

Update your app.module.ts file: You need to add the ServerTransferStateModule to your AppModule imports to transfer the state from the server to the client.

import { NgModule } from '@angular/core';
import { BrowserModule, BrowserTransferStateModule } from '@angular/platform-browser';
import { AppComponent } from './app.component';

@NgModule({
   declarations: [
      AppComponent
   ],
   imports: [
      BrowserModule.withServerTransition({ appId: 'my-app' }),
      BrowserTransferStateModule
   ],
   providers: [],
   bootstrap: [AppComponent]
})
export class AppModule {}

By following these steps, you can effectively implement Angular Universal in your Angular application to improve performance, SEO, and user experience.

Use NgRx

NgRx is a state management library that can help you manage the state of your application in a scalable and efficient manner.

ngRx is a state management library for Angular applications. It is based on the Redux pattern and provides a centralized store to manage the application state in a predictable way.

Steps to implement NgRx in Angular Application.

Install ngRx
Set up the store
Define actions
Define reducers
Define effects
Dispatch actions
Subscribe to the store

Here are the steps to use ngRx in an Angular application:

Install ngRx: You can install ngRx using npm or yarn. Run the following command in your terminal to install the required packages:
npm install @ngrx/store @ngrx/effects @ngrx/entity @ngrx/store-devtools

Set up the store: Create a store module and define your application state, actions, and reducers. The store module should import the StoreModule.forRoot() function from the @ngrx/store package.

Define actions: Actions describe the changes to the state that should occur in response to user interactions or other events. Each action should be defined as a class with a type property that uniquely identifies the action.

Define reducers: Reducers are pure functions that take the current state and an action as arguments and return a new state. Each reducer should handle one or more actions and update the relevant parts of the state.

Define effects: Effects are functions that listen for actions and perform side effects such as making HTTP requests, updating local storage, or dispatching other actions. Effects should be defined as a service and imported into the store module.

Dispatch actions: To update the state, you need to dispatch actions from your components or services. You can do this by importing the Store service from the @ngrx/store package and calling its dispatch() method with an instance of your action class.

Subscribe to the store: To read data from the store, you can subscribe to it using the select() method of the Store service. This method returns an observable that emits the current state whenever it changes.

That’s it! With these steps, you can use ngRx in your Angular application to manage the state in a predictable and scalable way.

Use AOT Compilation

Ahead-of-Time (AOT) compilation can improve the performance and scalability of your application by compiling your templates and code during the build process.

To use AOT compilation in an Angular application, follow these steps:

Update the application’s configuration
Update the application’s build command
Verify that the application builds successfully
Test the application

Update the application’s configuration: In the tsconfig.json file, set the target property to es5 or higher, and set the module property to es2015 or higher. This will ensure that the application’s code can be compiled with AOT.

Update the application’s build command: In the package.json file, update the build command to include the — aot flag. For example:

“build”: “ng build — aot”

Verify that the application builds successfully: Run the build command to verify that the application can be compiled with AOT. If there are any errors, fix them before proceeding.

Test the application: After the build is successful, test the application to verify that it works as expected. The AOT-compiled version of the application should be faster to load and execute than the non-AOT version.

Using AOT compilation can help improve the performance of an Angular application, especially on slower devices or networks. However, it does require additional setup and configuration, so make sure to test the application thoroughly after enabling AOT compilation.

Use Angular CLI

Angular CLI is a command-line interface tool that can help you quickly generate new components, services, and modules. It also has built-in support for testing, linting, and bundling your application.

Angular CLI (Command Line Interface) is a powerful tool that simplifies many common tasks when developing Angular applications.

It provides a set of commands for generating components, services, modules, and other features, as well as tools for building, testing, and deploying applications.

Let’s explore an easy way to use Angular CLI in the Angular application.

Creating a new project
Generating components, services, and other features
Running the application
Building the application
Running tests
Running end-to-end tests

Here are some of the ways you can use Angular CLI in an Angular application:

Creating a new project: You can use the ng new command to create a new Angular project. This command will generate a basic project structure with all the necessary files and dependencies.

Generating components, services, and other features: You can use the ng generate command to generate new components, services, modules, and other features. This command will create the necessary files and update the relevant configuration files (such as app.module.ts).

Running the application: You can use the ng serve command to start a development server and run the application in the browser. This command will watch for changes to the code and automatically reload the browser.

Building the application: You can use the ng build command to build the application for production. This command will create a set of optimized files that can be deployed to a web server.

Running tests: You can use the ng test command to run the application’s unit tests. This command will start a testing server and run the tests in the browser.

Running end-to-end tests: You can use the ng e2e command to run end-to-end tests using the Protractor testing framework. This command will start a server and run the tests in a browser environment. It plays an essential role in mastering AngularJS testing capabilities.

Angular CLI provides many other commands and options for managing Angular applications, so check the documentation for more information.

Using Angular CLI can help you streamline your development workflow and reduce the time and effort required to perform everyday tasks.

So, what are you waiting for? Adopt such best practices and scale your Angular application efficiently. Moreover, by following these practices, you can build a scalable Angular application that can easily accommodate changes and growth over time.