How to use TypeScript on backend ?

TypeScript, developed by Microsoft, enhances JavaScript by adding type safety, which significantly simplifies debugging and development. This guide will walk you through setting up a TypeScript backend with Node.js and Express, showing you how to leverage TypeScript’s robust features to prevent common runtime bugs and improve your code management.

Prerequisites:

• NodeJS: Basics of Node.js development.
• Express: Fundamental concepts of building web applications with Express.
• JavaScript: Familiarity with JavaScript syntax.

Project Setup and Module Installation:

Step 1: Run the following command in command prompt/bash/console to create a node project

npm init -y

Step 2: Adding the required dependencies using the following command.

npm i express 
npm i typescript ts-node @types/node @types/express --save-dev
npm i -D @types/express

Notice the devDependency for typescript. Typescript is only required through the development process, In the end, It will be compiled to VanillaJS for runtime. Learn more about types of dependencies.

Note: @types libraries are development dependencies that provide TypeScript definitions for Express and Node.

Project Structure:

Step 3: Configure Typescript using the following command.

npx tsc --init

It will generate tsconfig.json where you can define parameters for typescript like which ECMAScript version to use (like ES3 (default), ES5, ES2015), enable strict type checking or not. Learn more about typescript configuration.

Step 4: Creating an express server, here we have named it server.ts

// Importing module
import express from 'express';

const app = express();
const PORT:Number=3000;

// Handling GET / Request
app.get('/', (req, res) => {
    res.send('Welcome to typescript backend!');
})

// Server setup
app.listen(PORT,() => {
    console.log('The application is listening '
          + 'on port http://localhost:'+PORT);
})

Step 6: Configure package.json

Add the following line of code in package.json file, tsc command compiles typescript code to Vanilla JavaScript, while node server.js will take the generated Vanilla JavaScript file and start the server.

"scripts": {
 "build": "tsc",
 "start": " node server.js"
}

Step 7: Run the server using the following command.

npm run build
npm start

Output: Now open the http://localhost:3000 in any browser to see the server running.