TypeScript Features in Angular

Angular is built with TypeScript, a strongly typed superset of JavaScript that offers additional features such as classes and interfaces. These TypeScript features provide many advantages when developing Angular applications. In this guide, we’ll explore some important TypeScript features used in Angular.

Syntax

TypeScript is a superset of JavaScript, so all valid JavaScript code is also valid TypeScript code. Here’s an example of how TypeScript introduces new syntax and features to JavaScript:

class Person {
  constructor(public name: string, public age: number) { }
  
  sayHello() {
    console.log(`Hello, my name is ${this.name} and I'm ${this.age} years old.`);
  }
}

let me = new Person('John', 30);
me.sayHello();

Example

Here’s an example of how we can use TypeScript features in an Angular component:

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

interface User {
  name: string;
  email: string;
}

@Component({
  selector: 'app-users',
  template: `
    <ul>
      <li *ngFor="let user of users">{{ user.name }} - {{ user.email }}</li>
    </ul>
  `
})
export class UsersComponent {
  users: User[] = [
    { name: 'John', email: 'john@example.com' },
    { name: 'Jane', email: 'jane@example.com' },
  ];
}

Output

The above example will render a list of users with their names and email addresses.

Explanation

Here are some TypeScript features commonly used in Angular:

• Classes: TypeScript classes are used to define the structure and behavior of objects used in an Angular application. Components, services, and models are all examples of classes.
• Interfaces: TypeScript interfaces are used to define the shape of an object. In Angular, interfaces are often used to define the shape of data retrieved from an API.
• Type annotations: TypeScript allows you to add type annotations to variables, function parameters, and return types. This helps catch errors at compile time and enables better tooling support.
• Decorators: TypeScript decorators are used to add metadata to classes and their members. In Angular, decorators are used to mark a class as a component, service, or directive.

Use

TypeScript features are used throughout an Angular application, including:

• Defining components, services, and models with classes
• Defining API responses with interfaces
• Adding type annotations to variables, function parameters, and return types
• Adding metadata to classes with decorators

Important Points

• TypeScript is a superset of JavaScript that adds additional features such as classes, interfaces, and type annotations.
• TypeScript features provide many advantages when developing Angular applications, including clearer code and better tooling support.
• It is recommended to use TypeScript when developing Angular applications to take advantage of these features.

Summary

TypeScript brings powerful new features to JavaScript, making it a perfect match for building Angular applications. With classes, interfaces, type annotations, and decorators, TypeScript makes it easier to write and maintain complex applications while improving overall code quality.