How to Create a TypeScript-Driven REST API with Express - Complete Guide
I'm deploying to production and I tried several approaches but none seem to work. # Learning Objectives This complete guide will help you achieve the following learning goals: - Understand how to set up a TypeScript environment for a Node.js application. - Build a RESTful API using Express and TypeScript. - Implement best practices for type safety and code organization. ## Getting Started Before diving into the implementation, ensure you have the following prerequisites: - Node.js installed on your machine (version 14 or higher). - A code editor of your choice (e.g., Visual Studio Code). ## Step 1: Setting Up Your TypeScript Environment Begin by creating a new directory for your project and initializing a new npm package: ```bash mkdir typescript-express-api cd typescript-express-api npm init -y ``` Next, install TypeScript and Express: ```bash npm install typescript express @types/express --save ``` After installing, initialize TypeScript: ```bash tsc --init ``` This command generates a `tsconfig.json` file where you can customize TypeScript options. ## Step 2: Creating the Express Server Create a new file named `server.ts` in your project directory: ```typescript import express from 'express'; const app = express(); const PORT = process.env.PORT || 3000; app.use(express.json()); app.get('/', (req, res) => { res.send('Welcome to the TypeScript REST API!'); }); app.listen(PORT, () => { console.log(`Server is running on http://localhost:${PORT}`); }); ``` This code sets up a basic Express server that responds to requests at the root URL. ## Step 3: Creating API Routes Let's enhance your API by adding routes. Create a new folder named `routes` and a file named `userRoutes.ts`: ```typescript import express from 'express'; const router = express.Router(); // Define a User interface interface User { id: number; name: string; } // Simulated user database const users: User[] = [{ id: 1, name: 'John Doe' }]; // GET all users router.get('/users', (req, res) => { res.json(users); }); // POST a new user router.post('/users', (req, res) => { const newUser: User = req.body; users.push(newUser); res.status(201).json(newUser); }); export default router; ``` Now import and use this route in your `server.ts`: ```typescript import userRoutes from './routes/userRoutes'; app.use('/api', userRoutes); ``` ## Step 4: Compiling and Running Your Application To compile and run your TypeScript application, update your `package.json` scripts section: ```json "scripts": { "start": "tsc && node build/server.js" } ``` Now, compile your TypeScript files and start the server: ```bash npm start ``` Navigate to `http://localhost:3000/api/users` to see your API in action. ## Best Practices - Organize your code into separate modules for routes, controllers, and services. - Utilize interfaces to define the structure of your data. - Use middleware for validation and error handling to enhance your API. ## Conclusion Congratulations on building a TypeScript-driven REST API with Express! By following this complete guide, you have implemented best practices and gained a solid foundation in using TypeScript with Node.js. Happy coding!