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What is Count App?

Count App is a lightweight Angular application that demonstrates the fundamentals of building interactive web applications with Angular 21. It implements a simple counter interface where users can increment, decrement, and reset a numeric value. While the functionality is straightforward, Count App serves as an excellent reference for learning modern Angular development patterns and best practices.

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Architecture Overview

Count App is built with cutting-edge Angular features and tools:

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Angular 21

The application leverages the latest Angular framework (version 21.2.0) with modern component architecture and standalone components.

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Signals

The app component uses Angular signals for reactive state management: 
export class App {
  protected readonly title = signal('count-app');
}

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Server-Side Rendering (SSR)

Count App includes full SSR support with:
  • Client hydration with event replay for improved performance
  • Express server configuration for production deployment
  • Optimized initial page load
export const appConfig: ApplicationConfig = {
  providers: [
    provideBrowserGlobalErrorListeners(),
    provideRouter(routes), 
    provideClientHydration(withEventReplay())
  ]
};

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Tailwind CSS

The project is configured with Tailwind CSS 4.1.12 for modern, utility-first styling: 
@import 'tailwindcss';

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Vitest Testing

Unit tests are powered by Vitest, a fast and modern test runner designed for Vite-based projects.

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Key Features

Component-Based Architecture

Modular design with a dedicated CountPageComponent that encapsulates counter logic

Event Handling

Click event binding demonstrating Angular’s template syntax and event system

State Management

Simple yet effective state management with boundary validation

Routing

Angular Router configuration with route definitions and lazy loading support

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Application Structure

The counter logic is implemented in the CountPageComponent (src/app/count/counter.components.ts): 
export class CountPageComponent {
  counter = 10;

  incrementby(value: number) {
    this.counter = Math.max(0, this.counter + value);
  }

  reset() {
    this.counter = 0
  }
}
Key implementation details:
  • Initial state: Counter starts at 10
  • Boundary validation: Uses Math.max(0, ...) to prevent negative values
  • Method-based actions: Clean separation of increment and reset logic

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When to Use Count App as a Learning Resource

Count App is ideal for developers who want to understand:
  • Angular component fundamentals
  • Event binding and template syntax
  • SSR configuration and hydration
  • Modern Angular project structure
  • Integration of Tailwind CSS with Angular
This is a learning application and not intended for production use as-is. It demonstrates core concepts that can be applied to real-world projects.

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Next Steps

Ready to get started? Follow the quickstart guide to install dependencies, run the development server, and interact with the counter application.

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Technology Stack

TechnologyVersionPurpose
Angular21.2.0Frontend framework
TypeScript5.9.2Type-safe development
Tailwind CSS4.1.12Utility-first styling
Express5.1.0SSR server
Vitest4.0.8Unit testing
RxJS7.8.0Reactive programming

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