TypeScript 5.3 launches today
(20 November 2023)

TypeScript is a superset of JavaScript that adds static typing to the language. It can be particularly beneficial for app developers as it helps catch errors during development, improves code maintainability, and provides better tooling support. Here are some ways app developers can use TypeScript along with detailed descriptions and code examples:

1. Setting up a TypeScript project:

Install TypeScript:

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npm install -g typescript

Initialize a TypeScript project:

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tsc --init

This creates a tsconfig.json file where you can configure TypeScript settings.

2. Basic TypeScript Types:

Example 1: Declaring variables with types

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// basic types
let username: string = "John";
let age: number = 30;
let isDeveloper: boolean = true;

3. Functions and Interfaces:

Example 2: Function with type annotations

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// function with type annotations
function greet(name: string): string {
return `Hello, ${name}!`;
}
console.log(greet("John")); // Output: Hello, John!

Example 3: Interfaces for object structures

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// interface for an object
interface Person {
name: string;
age: number;
}
// function using interface
function printPerson(person: Person): void {
console.log(`${person.name} is ${person.age} years old.`);
}
const user: Person = { name: "Alice", age: 25 };
printPerson(user); // Output: Alice is 25 years old.

4. Classes and Inheritance:

Example 4: Classes and inheritance

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// class and inheritance
class Animal {
constructor(public name: string) {}
makeSound(): void {
console.log("Some generic sound");
}
}
class Dog extends Animal {
makeSound(): void {
console.log("Bark! Bark!");
}
}
const myDog = new Dog("Buddy");
myDog.makeSound(); // Output: Bark! Bark!

5. Generics:

Example 5: Using generics

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// generic function
function identity<T>(value: T): T {
return value;
}
const result = identity<number>(42);
console.log(result); // Output: 42

6. Modules and Namespaces:

Example 6: Modules

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// module example
// math.ts
export function add(a: number, b: number): number {
return a + b;
}
// app.ts
import { add } from "./math";
const sum = add(3, 5);
console.log(sum); // Output: 8

7. Type Declarations for External Libraries:

Example 7: Using external libraries with type declarations

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// Example using Axios with TypeScript
import axios from 'axios';
interface Post {
userId: number;
id: number;
title: string;
body: string;
}
axios.get<Post>('https://jsonplaceholder.typicode.com/posts/1')
.then(response => {
const post: Post = response.data;
console.log(post.title); // Output: Post Title
})
.catch(error => {
console.error(error);
});

These examples cover some of the fundamental aspects of using TypeScript in app development. Depending on the type of application (web, mobile, desktop), you may encounter additional features and patterns specific to those platforms.