TypeScript & Angular

In this tutorial, we will explore how to use TypeScript with Angular to build strongly typed components, improving code quality and maintainability.

TypeScript with Angular

Angular is built with TypeScript, which makes it easier to incorporate TypeScript's strong typing capabilities when building components. By typing your component's properties and methods, you can catch errors at compile-time, reducing runtime errors and making your code more maintainable.

Creating a Typed Component

To create a typed component, define an interface or type for the component's properties and methods. Then, extend the Component class and implement the interface or type.

TypeScript

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

interface CounterProps {
  count: number;
}

@Component({
  selector: 'app-counter',
  template: `
    <h2>Count: {{ count }}</h2>
    <button (click)="increment()">Increment</button>
  `,
})
export class CounterComponent implements CounterProps {
  count = 0;

  increment(): void {
    this.count++;
  }
}

In this example, we define a CounterComponent that maintains a count property and has an increment method. By implementing the CounterProps interface, we ensure that the component uses the correct types for properties and methods.

Creating a Typed Service

To create a typed service, define an interface or type for the service's properties and methods. Then, create a class implementing the interface or type, and use the @Injectable() decorator to make it available for dependency injection.

TypeScript

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

interface CounterServiceProps {
  count: number;
  increment: () => void;
}

@Injectable({
  providedIn: 'root',
})
export class CounterService implements CounterServiceProps {
  count = 0;

  increment(): void {
    this.count++;
  }
}

In this example, we define a CounterService that maintains a count property and has an increment method. By implementing the CounterServiceProps interface, we ensure that the service uses the correct types for properties and methods.

Conclusion

In this tutorial, we have explored how to use TypeScript with Angular to build strongly typed components and services, improving code quality and maintainability. As you continue learning TypeScript and Angular, consider using TypeScript to enforce strong typing and reduce errors in your Angular projects.