5 Common Angular Pitfalls and How to Avoid Them

Source: Dev.to

Beware

Angular is a powerful framework, but even experienced developers can fall into common traps that hurt performance, maintainability, or readability. Falling victim to these small issues can quietly fuel that all‑too‑familiar developer ailment: imposter syndrome.

In this article, I’ll walk through five common Angular pitfalls I see in real‑world applications and show how to avoid them with practical examples and best practices.

1. Misusing Lifecycle Hooks (ngOnInit, ngOnChanges)

The problem

Many developers overuse ngOnInit or put heavy logic in ngOnChanges, causing unnecessary re‑renders or complicated debugging.

The solution

Keep lifecycle hooks focused on initialization or change detection that actually depends on input changes.

• Move business logic to services instead of components.

Bad example

ngOnInit() {
  this.loadData();
  this.processData(); // heavy computation here
}

Better example

ngOnInit() {
  this.loadData();
}

private loadData() {
  this.dataService.getData().subscribe(data => {
    this.processData(data);
  });
}

Why it matters

Separating concerns keeps components lightweight, testable, and easier to maintain.

2. Overusing Two‑Way Binding ([(ngModel)])

The problem

Two‑way binding is convenient, but overusing [(ngModel)]—especially in larger forms—can lead to hidden side effects and messy validation logic.

The solution

• Use Reactive Forms for anything non‑trivial.
• Reserve ngModel for very simple inputs.

Reactive forms example

import { FormGroup, FormControl, Validators } from '@angular/forms';

form = new FormGroup({
  name: new FormControl('', Validators.required),
  email: new FormControl('', [
    Validators.required,
    Validators.email
  ])
});

<form [formGroup]="form" (ngSubmit)="onSubmit()">
  <label>
    Name:
    <input formControlName="name" />
  </label>

  <label>
    Email:
    <input formControlName="email" />
  </label>

  <button type="submit">Submit</button>
</form>

Why it matters

Reactive forms make validation, testing, and debugging much more predictable as your app grows.

3. Improper State Management (BehaviorSubject vs Signals)

The problem

Many Angular applications rely heavily on BehaviorSubject for all state, even when the state is simple. This can lead to unnecessary RxJS boilerplate and more complex code than needed.

The solution

• Use Signals (Angular 16+) for simple reactive state.
• Use BehaviorSubject or NgRx for shared or complex state.
• Keep state logic in services, not components.

Signals example

import { signal } from '@angular/core';

export class CounterService {
  counter = signal(0);

  increment() {
    this.counter.update(value => value + 1);
  }
}

Why it matters

If you’re already deep into NgRx, Signals won’t replace it—but they’re a great fit for local or service‑level state. Signals provide clean, readable reactivity without the overhead of observables when your state doesn’t require complex streams or operators.

4. Forgetting trackBy in *ngFor

The problem

When rendering lists without a trackBy function, Angular destroys and recreates DOM elements whenever the list changes—even if only one item was updated. This can cause unnecessary re‑renders and performance issues, especially with larger lists.

The solution

Always provide a trackBy function when iterating over collections.

Good practice example

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

trackById(index: number, item: { id: number }) {
  return item.id;
}

Why it matters

Using trackBy ensures Angular only updates the elements that actually changed, significantly improving rendering performance.

5. Inefficient Change Detection

The problem

Default change detection can cause unnecessary checks across the component tree, which leads to degraded performance in larger applications.

The solution

• Use ChangeDetectionStrategy.OnPush.
• Pass immutable data to components.
• Avoid unnecessary template bindings.

Example

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

@Component({
  selector: 'app-user-card',
  templateUrl: './user-card.component.html',
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class UserCardComponent {
  @Input() user!: User;
}

Why it matters

OnPush dramatically reduces unnecessary change‑detection cycles and helps keep your UI fast and responsive.