Node.js 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
// app.ts
import express, { Request, Response } from 'express';
interface User {
id: number;
name: string;
}
const app = express();
app.use(express.json());
// In-memory database
let users: User[] = [];
// Get all users
app.get('/users', (req: Request, res: Response) => {
res.json(users);
});
// Add new user
app.post('/users', (req: Request, res: Response) => {
const user: User = req.body;
users.push(user);
res.status(201).json(user);
});
const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
console.log(`Server running on port ${PORT}`);
});
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"]
}
Key Compiler Options:
target: Specify ECMAScript target versionmodule: Specify module code generationstrict: Enable all strict type checking optionsoutDir: Redirect output structure to the directoryrootDir: Specify the root directory of input files
Why Use TypeScript with Node.js?
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
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
