Node TypeScript

What is TypeScript?

TypeScript is a superset of JavaScript that adds optional static typing.

It helps you catch errors early and write safer, more maintainable code.

Take a look at our TypeScript tutorial for more details.

Using TypeScript with Node.js

To use TypeScript in Node.js projects, you need to install TypeScript and a type definition manager:

npm install -g typescript
npm install --save-dev @types/node

Write your code in .ts files and compile them to JavaScript with:

tsc yourfile.ts

Setting Up a TypeScript Project

1. Initialize a new Node.js project

npm init -y

2. Install TypeScript and type definitions

npm install --save-dev typescript @types/node

3. Initialize TypeScript configuration

npx tsc --init

TypeScript Basics

1. Basic Types

// Primitive types
let isDone: boolean = false;
let count: number = 10;
let name: string = 'TypeScript';

// Arrays
let numbers: number[] = [1, 2, 3];
let names: Array<string> = ['Alice', 'Bob'];

// Tuples
let user: [string, number] = ['Alice', 25];

// Enums
enum Color {Red, Green, Blue}
let color: Color = Color.Green;

2. Interfaces and Types

// Interface
interface User {
  id: number;
  name: string;
  email?: string;  // Optional property
}

// Type alias
type Point = {
  x: number;
  y: number;
};

// Using the interface
function printUser(user: User) {
  console.log(`User: ${user.name}`);
}

TypeScript with Node.js

1. Creating a Simple HTTP Server

// server.ts
import http from 'http';

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello, TypeScript!');
});

const PORT = process.env.PORT || 3000;
server.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});

2. Using TypeScript with Express

# Install required packages
npm install express
npm install --save-dev @types/express

TypeScript Configuration

tsconfig.json

{
  "compilerOptions": {
    "target": "es2018",
    "module": "commonjs",
    "outDir": "./dist",
    "rootDir": "./src",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules"]
}

Note: Key Compiler Options: target: Specify ECMAScript target version module: Specify module code generation strict: Enable all strict type checking options outDir: Redirect output structure to the directory rootDir: Specify the root directory of input files

Why Use TypeScript with Node.js?

Note: Benefits of TypeScript: Type Safety: Catch errors at compile time rather than runtime Better IDE Support: Superior autocompletion and code navigation Self-Documenting Code: Types serve as documentation Easier Refactoring: Safely rename variables and update code Gradual Adoption: Add types incrementally to existing JavaScript code

Warning: When to Use TypeScript: Large codebases with multiple developers APIs where type safety is critical Projects that will be maintained long-term When working with complex data structures