Getting Started with Angular: From Basics to Signals

Introduction

Angular is a robust, opinionated framework for building Single-Page Applications (SPAs) with TypeScript. Whether you’re an experienced developer or dipping your toes into front-end frameworks, Angular offers a comprehensive toolkit—from routing and forms to HttpClient and the new Signals-based reactivity model introduced in Angular v16.

In this post, we’ll begin with a super-simple “Hello World,” explore essential Angular concepts, and conclude with a small, fully featured to-do application—demonstrating both classical data binding patterns and the new Signals feature. Along the way, we’ll highlight best practices, common pitfalls, and even take a quick look at Angular’s future trajectory.

Step 1: Setting Up the Environment

Before writing any code, make sure you have Node.js (v14 or higher) and npm installed. With Node ready, install the Angular CLI globally:

npm install -g @angular/cli

Now you can run ng commands from your terminal, such as creating new projects, serving them locally, or generating boilerplate code for components, services, pipes, and more.

Step 2: Creating a Hello World App

Let’s start with the classic “Hello World.” Create a new project:

ng new hello-angular
cd hello-angular
ng serve --open

Once the development server starts, your browser automatically opens http://localhost:4200. By default, you’ll see a scaffolded Angular landing page. Let's replace it:

<!-- src/app/app.component.html -->
<h1>Hello Angular!</h1>

Save the file, and your browser instantly displays “Hello Angular!” You’ve officially created your first Angular app.

Gotcha: Always confirm you’re in the correct project folder; if a new browser doesn’t open or you see an error, confirm the path.

Step 3: Components & Data Binding

Components are the fundamental building blocks of an Angular application. They consist of an HTML template, TypeScript class, and optional CSS styling. Data binding helps keep your model and view in sync—Angular supports both one-way and two-way patterns.

For example:

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

@Component({
  selector: 'app-hello',
  template: `
    <h2>{{title}}</h2>
    <p>Welcome, {{name}}!</p>
    <button (click)="sayHello()">Click Me</button>
  `,
  styleUrls: ['./hello.component.css']
})
export class HelloComponent {
  title = 'Hello Component';
  name = 'Angular Developer';

  sayHello() {
    alert(`Hello, ${this.name}!`);
  }
}

In the template, ｛｛title ｝｝ is a one-way binding, while (click)="sayHello()" denotes an event binding. Let’s include this component in AppComponent:

<!-- src/app/app.component.html -->
<app-hello></app-hello>

Angular then compiles your custom <app-hello>element and renders your new greeting.

Best Practice: Keep components small, single-purpose, and name them clearly. This helps maintain a clean, navigable codebase.
Gotcha: If the CLI auto-generates “spec” files (for tests) and you’re not using them yet, don’t forget to either remove them or actually write tests (preferably the latter!).

Step 4: Introducing Signals in Angular

Angular “signals” are a newer reactivity feature designed to optimize change detection by providing a more explicit, fine-grained subscription model. This approach can significantly reduce overhead in complex apps by limiting re-renders to just the pieces of UI relying on a specific signal.

Suppose we have a simple count signal that can be consumed by multiple components:

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

export const counterSignal = signal(0);

You can update the signal value anywhere:

counterSignal.update(value => value + 1);

Anywhere you reference counterSignal() in a template or component, Angular re-renders only that section upon changes—unlike the traditional zone-based or “everything re-checks” approach.

Gotcha: Signals are still relatively new in Angular’s ecosystem. They coexist with existing zone-based change detection and RxJS. Be mindful when mixing them in large, established codebases.
Best Practice: Consider signals for stateful data that changes frequently, but keep well-established patterns (like RxJS, NgRx, or simple service-based state) if your team is more comfortable with those.

Step 5: Building a Fully Featured To-Do App

Now let’s piece it all together by building a small to-do application. It will demonstrate typical Angular patterns like component structure, services, and show how signals can simplify data reactivity.

5a: Set Up the Project

ng new todo-app
cd todo-app
ng serve --open

We’ll keep everything in one module for simplicity, but real projects often break functionalities into multiple feature modules.

5b: Create a Model and Service

// src/app/todo.model.ts
export interface Todo {
  id: number;
  text: string;
  completed: boolean;
}

Our TodoService will manage to-dos using Angular signals:

// src/app/todo.service.ts
import { Injectable, signal } from '@angular/core';
import { Todo } from './todo.model';

@Injectable({
  providedIn: 'root',
})
export class TodoService {
  // A signal holding an array of todos
  todos = signal<Todo[]>([]);

  addTodo(text: string) {
    const newTodo: Todo = {
      id: Date.now(),
      text,
      completed: false,
    };
    // Use update() to modify the signal's state immutably
    this.todos.update(todos => [...todos, newTodo]);
  }

  toggleTodo(id: number) {
    this.todos.update(todos =>
      todos.map(todo =>
        todo.id === id ? { ...todo, completed: !todo.completed } : todo
      )
    );
  }

  removeTodo(id: number) {
    this.todos.update(todos => todos.filter(todo => todo.id !== id));
  }
}

5c: Create a Todo List Component

ng generate component todo-list

Inside todo-list.component.ts, we inject the TodoService, read the todos signal, and build the UI:

import { Component } from '@angular/core';
import { TodoService } from '../todo.service';

@Component({
  selector: 'app-todo-list',
  templateUrl: './todo-list.component.html',
  styleUrls: ['./todo-list.component.css']
})
export class TodoListComponent {
  newTodoText = '';

  constructor(public todoService: TodoService) {}

  addTodo() {
    if (this.newTodoText.trim()) {
      this.todoService.addTodo(this.newTodoText);
      this.newTodoText = '';
    }
  }

  toggleTodo(id: number) {
    this.todoService.toggleTodo(id);
  }

  removeTodo(id: number) {
    this.todoService.removeTodo(id);
  }
}

The HTML template (todo-list.component.html):

<div>
  <h2>My Angular To-Do List</h2>
  <input [(ngModel)]="newTodoText" placeholder="Add a new to-do" />
  <button (click)="addTodo()">Add</button>

  <ul>
    <li *ngFor="let todo of todoService.todos()">
      <input 
        type="checkbox" 
        [checked]="todo.completed" 
        (change)="toggleTodo(todo.id)"
      />
      <span [ngClass]="{ 'completed': todo.completed }">
        {{ todo.text }}
      </span>
      <button (click)="removeTodo(todo.id)">x</button>
    </li>
  </ul>
</div>

.completed {
  text-decoration: line-through;
  color: gray;
}

button {
  margin-left: 8px;
}

Now you have a fully functional to-do app demonstrating basic Angular patterns (components, services) plus new signals-based reactivity.

Step 6: Best Practices & Common Gotchas

Use Angular CLI Wisely: Generate components, pipes, and services via ng generate for structure consistency and best naming conventions.
Module Organization: Break your app into separate modules for each feature (e.g.TodoModule, UserModule) to improve maintainability and enable lazy loading.
Observables vs Signals: Many codebases still rely on RxJS for streams and advanced operators. Signals can coexist with observables but often serve simpler reactivity needs.
Forms Handling: For more complex forms, Angular’s ReactiveFormsModule is extremely powerful—especially when combined with signals for state changes.
Common Performance Pitfalls: Overuse of “heavy” structural directives *ngFor without trackBy, or not unsubscribing from Observables inngOnDestroy can lead to memory leaks or performance bottlenecks.
Testing & Linting: Angular CLI automatically sets up a testing environment using Karma andJasmine. Don’t skip writing tests—especially for critical services and complex components.

Step 7: The Future of Angular

Angular has evolved significantly since its inception (calling back to “AngularJS” days). Today’s Angular stands on a modern foundation (Ivy compiler, CLI, TypeScript-first approach) and continues to push forward. Some key directions:

Standalone Components: A new approach to building Angular apps without the need forNgModule overhead. This feature reduces boilerplate and simplifies the learning curve.
Signals: Already introduced in Angular 16, signals point to a future where Angular’s change detection could become more fine-grained and performance-friendly. Expect continued improvements and expansions around signals-based reactivity.
More Strictness: With each release, Angular pushes for stricter TypeScript settings by default, aiming to catch errors early and improve code quality.
Incremental Updates: Angular typically releases updates twice a year. These are usually non-breaking or minimally disruptive, but stay on top of the release cycle to avoid big jump migrations.

The Angular team has been focusing on developer experience, making the framework simpler to learn and more powerful in performance-critical scenarios.

Conclusion

We started with the most basic Angular “Hello World,” explored components and data binding, introduced the new signals API for efficient reactivity, and ended with a fully functional to-do application. Throughout, we looked at best practices for code organization, the interplay of signals with classical RxJS solutions, and potential pitfalls.

Whether you’re staying purely within a classical Angular approach or adopting signals, you now have the groundwork to build a modern, robust Angular application. Keep an eye on new developments in Angular’s ecosystem—like standalone components and further signals enhancements—to stay on the cutting edge.

Happy coding in Angular!
– Nate