angular developer mistakes

7 Mistakes I Made As A Front-End Angular Developer

Angular developers’ primary focus is to create and validate code, which is written in JavaScript, CSS, and HTML. JavaScript is a versatile and constantly evolving programming language. In this article, we will discuss the most common Angular developer mistakes. As a developer, it is not good to adopt habits, which are prone to making mistakes.

Direct DOM Manipulation

In most cases, Angular developers should avoid direct DOM manipulation because it can introduce potential issues such as performance problems, memory leaks, and security vulnerabilities.

@Component({ … })

export class BasicComponent {

 constructor(private _elementRef: ElementRef) {}


 init() {

   this._elementRef.nativeElement.mySelectorTag = ‘ ‘;

   document.getElementById(‘ ‘);



Instead, Angular provides a variety of high-level APIs that abstract away the complexities of working with the DOM directly. For example, the Renderer2 API provides a safer way to interact with the DOM. And, the ChangeDetectorRef API can help optimize change detection.

@Component({ … })

export class BasicComponent {

 constructor(private _renderer2: Renderer2,

private _elementRef: ElementRef) {}

 init() {

   this._renderer2.setProperty(this._elementRef, ‘correct_property’, true);



Not Using a Strong Typing System

One of the main benefits of using Typescript is its strong typing system, which helps developers catch errors at compile time rather than runtime. However, some Angular 2 developers don’t take advantage of this feature, either by not defining types or by using any type too liberally. This can lead to errors, reduce code readability and make it harder to maintain the code.

If you choose not to use a strong typing system in Angular, it can result in several potential mistakes or issues:

  1. Increased likelihood of runtime errors: Without a strong typing system, it can be more difficult to catch type-related errors during development. This can result in runtime errors that are harder to debug and fix.
  2. Increased maintenance costs: When working with a large codebase, not having a strong typing system can make it harder to maintain and update the code. This can lead to increased development costs and slower development times.
  3. Lower code quality: Code that lacks strong typing may be less readable and harder to understand. This can lead to lower code quality and longer development times.

Not Following Best Practices for Dependency Injection

Dependency injection is a popular design pattern used in software development to decouple dependencies between components. The pattern involves passing dependencies as arguments to a component’s constructor rather than creating them within the component itself. By doing so, the component becomes more modular, testable, and easier to maintain.

Consequences of not following best practices for dependency injection.

  1. Code becomes tightly coupled

    Suppose you have a component that directly creates an instance of a dependency rather than accepting it as a constructor argument. In that case, you’ll have to modify the component’s code every time the dependency’s implementation changes. This kind of tight coupling can lead to a lot of headaches down the line.
  2. Testing becomes harder

    When components accept dependencies as constructor arguments, it’s easy to substitute them with mock objects during testing. This allows you to isolate the component under test and verify its behavior independently of its dependencies.

    When you don’t follow best practices for dependency injection, testing becomes much harder. If a component creates its dependencies internally, you’ll have to rely on integration testing, which is more time-consuming and difficult to set up.
  3. Code becomes harder to reason about

    When you follow best practices for dependency injection, your code becomes more modular, and each component’s responsibilities become clear. This makes it easier to reason about the code and understand how each component fits into the overall system.

    However, when you don’t follow best practices for dependency injection, your code becomes harder to reason about. If a component creates its dependencies internally, it’s not immediately clear where those dependencies came from or how they’re being used. This can make it much harder to debug and maintain the code over time. 
  4. Code becomes less reusable

    Finally, not following best practices for dependency injection can make your code less reusable. When you decouple components through dependency injection, you make it easier to reuse those components in other parts of your system or even in other projects entirely.

    When you don’t follow best practices for dependency injection, you may end up with tightly coupled code that’s difficult to reuse. This can lead to a lot of duplicate code and wasted effort.

Forgot to Unsubscribe from the Listed Events

It’s important to unsubscribe from events that are subscribed to in components or services to prevent memory leaks. If you forget to unsubscribe, the subscription will remain active even after the component or service has been destroyed, leading to unnecessary memory consumption and potential performance issues.

To avoid this issue, Angular provides the OnDestroy lifecycle hook, which is called just before a component or service is destroyed. You can use this hook to unsubscribe from any subscriptions that were made in the ngOnInit hook or elsewhere in the component or service.

Not Understanding Change Detection

One common mistake that Angular developers make is not fully understanding how change detection works in the framework. This can lead to performance issues, unexpected behavior, and difficult-to-debug problems in Angular applications.

Change detection is the mechanism that Angular uses to detect changes in the application state and update the user interface accordingly. By default, Angular uses a strategy called “default change detection”, which involves checking the entire component tree for changes every time change detection is run. This can be computationally expensive, especially for large applications with complex component trees.

The mistake that Angular developers often make is not optimizing change detection for performance. This can be done by using a different change detection strategy, such as “OnPush”. The OnPush strategy is based on immutable data and only checks for changes in the input properties of a component. This can significantly improve performance by reducing the scope of change detection.

Another common mistake is not understanding the relationship between change detection and asynchronous code, such as observables and promises. Angular uses a “zone” system to track asynchronous tasks and detect when they are complete. If developers are not careful, they can inadvertently trigger change detection too often, leading to performance issues and other problems.

To avoid these mistakes, Angular developers should take the time to fully understand how change detection works in the framework and optimize it for performance. They should also be mindful of the relationship between change detection and asynchronous code and use best practices for handling asynchronous tasks in Angular applications.

Not Using Reactive Programming

One of the common angular developer mistakes make is not using reactive programming in their applications. Reactive programming is a programming paradigm that is focused on handling asynchronous data streams and how they change over time. Angular has built-in support for reactive programming through the use of the RxJS library.

By not using reactive programming techniques and tools, Angular developers might rely on traditional imperative programming techniques such as callbacks and promises. This could lead to less efficient and more error-prone code that might be difficult to maintain and scale.

Using reactive programming techniques and RxJS in Angular applications can lead to more responsive, scalable, and maintainable code. By easily handling complex data flows, responding to user input in real time, and making code more modular and testable, developers can avoid errors and build more robust applications.

To avoid the mistake of not using reactive programming, Angular developers should invest time in learning and understanding the concepts of reactive programming and how to effectively use RxJS in their applications. This will lead to better code quality, improved performance, and increased productivity.

Not Using Data Binding Correctly

Data binding is a powerful feature in Angular. It allows developers to establish two-way communication between the component and the user interface.

The mistake that Angular developers often make is not understanding the different types of data binding and when to use each one. Following are the four diverse types of data binding in Angular:

  1. Interpolation binding: It is used for binding data from the component to the view.
  2. Property binding: It is used for binding a property of a DOM element to a property of the component.
  3. Event binding: It is used for binding an event of a DOM element to a method of the component.
  4. Two-way binding: It is used for creating a bi-directional data flow between the view and the component.

Another mistake is not understanding how data binding affects performance. Binding to complex data structures or binding in a loop can be computationally expensive and slow down the application.

Beginners may not understand the binding syntax correctly and use () instead of [] or using [()] where it’s not required.


In conclusion, Angular is a powerful framework that can be used to build robust and scalable applications. However, there are some common angular developer mistakes. It includes not understanding change detection, not using reactive programming, not using observables correctly, and not using data binding correctly.

To avoid these angular developer mistakes, they should invest time in learning and understanding the key concepts of Angular, including reactive programming and observables, data binding, and change detection. They should also be aware of best practices and use the built-in tools and features provided by Angular. This will help them to write clean, efficient, and maintainable code.

By avoiding these angular developer mistakes, they can build high-quality applications that are responsive, scalable, and easy to maintain.

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