Top 5 Angular Errors to Steer Clear Of

Angular is a popular and powerful JavaScript framework used for building web applications. Despite its popularity, many developers make common mistakes that can impact the performance and functionality of their applications. In this tutorial, we will discuss the top 5 Angular mistakes and how to avoid them.

1. Not Using TrackBy Function in ngFor Directive:

One common mistake that developers make when using Angular’s ngFor directive is not using the trackBy function. The trackBy function allows Angular to track the unique identity of each item in a collection, which can improve the performance of rendering lists in Angular applications.

To avoid this mistake, always use the trackBy function when iterating over a collection in the ngFor directive. For example:

<div *ngFor="let item of items; trackBy: trackByFunction">
  {{ item.name }}
</div>

trackByFunction(index, item) {
  return item.id;
}

In this example, the trackByFunction returns the unique id of each item in the collection, allowing Angular to efficiently track changes in the collection and update the DOM accordingly.

1. Not Using Angular’s Dependency Injection System:

Angular’s dependency injection system is a powerful feature that allows developers to easily inject services, components, and other dependencies into their Angular applications. However, many developers make the mistake of not using Angular’s dependency injection system, which can lead to code that is difficult to maintain and test.

To avoid this mistake, always use Angular’s dependency injection system to inject dependencies into your components and services. For example, instead of manually creating instances of services in your components, use Angular’s providedIn property to declare the service in the module and inject it into the component:

@Injectable({
  providedIn: 'root'
})
export class DataService {
  // service code
}

And then inject the service into the component constructor:

constructor(private dataService: DataService) { }

By using Angular’s dependency injection system, you can easily manage dependencies in your Angular applications and ensure that your code is more maintainable and testable.

1. Not Using Angular Forms and Form Validation:

Another common mistake that developers make in Angular is not using Angular forms and form validation. Angular provides a powerful Forms module that allows developers to create and manage forms in their applications, as well as validate user input.

To avoid this mistake, always use Angular forms and form validation when building forms in your Angular applications. Angular forms provide features such as form controls, form groups, and form validation directives that make it easy to create and validate forms in Angular applications.

For example, you can create a form in your component template using Angular’s reactive forms approach:

<form [formGroup]="myForm" (ngSubmit)="submitForm()">
  <input type="text" formControlName="name"/>
  <button type="submit">Submit</button>
</form>

And then create the form controls and validation rules in your component class:

myForm = new FormGroup({
  name: new FormControl('', Validators.required)
});

By using Angular forms and form validation, you can create robust and user-friendly forms in your Angular applications that handle user input validation and error handling.

1. Not Optimizing Change Detection:

Angular’s change detection mechanism is a fundamental feature that automatically updates the DOM when the application’s data changes. However, many developers make the mistake of not optimizing change detection in their Angular applications, which can lead to performance issues and inefficient rendering.

To avoid this mistake, always optimize change detection in your Angular applications by using techniques such as OnPush change detection strategy and immutable data structures. The OnPush change detection strategy tells Angular to only check for changes in components that have inputs bound to them, reducing the number of unnecessary checks and improving performance.

Additionally, using immutable data structures such as Immutable.js or RxJS Observables can further improve the performance of change detection in Angular applications. By ensuring that your data is immutable and using the OnPush change detection strategy, you can optimize change detection in your Angular applications and improve performance.

1. Not Handling Errors and Exceptions Properly:

Finally, a common mistake that developers make in Angular is not handling errors and exceptions properly. Angular provides features such as error handling mechanisms, interceptors, and error handlers that allow developers to gracefully handle errors and exceptions in their applications, preventing crashes and improving user experience.

To avoid this mistake, always use Angular’s error handling mechanisms to handle errors and exceptions in your Angular applications. For example, you can create a global error handler service that intercepts HTTP errors and displays error messages to the user:

@Injectable()
export class ErrorHandlerService implements ErrorHandler {
  handleError(error: any): void {
    // handle error
  }
}

And then provide the error handler service in your application module:

{ provide: ErrorHandler, useClass: ErrorHandlerService }

By properly handling errors and exceptions in your Angular applications, you can improve the reliability and user experience of your application and prevent crashes and unexpected behavior.

In conclusion, by avoiding these top 5 Angular mistakes and following best practices in Angular development, you can build robust, performant, and user-friendly web applications with Angular. By using features such as trackBy function, dependency injection, Angular forms, optimized change detection, and proper error handling, you can avoid common pitfalls and build high-quality Angular applications.