How to Set Up and Use TypeScript in a NodeJs Project

Introduction

TypeScript is a strongly typed superset of JavaScript that compiles to plain JavaScript. Using TypeScript in Node.js improves code quality and maintainability. This guide will walk you through setting up a Node.js project with TypeScript.

Prerequisites

Ensure you have the following installed:

Node.js (Download from nodejs.org)
npm or yarn (npm comes with Node.js)
TypeScript (Install globally or per project)

Setting Up a TypeScript Project

Step 1: Initialize a Node.js Project

mkdir my-typescript-node
cd my-typescript-node
npm init -y

This creates a package.json file.

Step 2: Install TypeScript and Dependencies

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

Step 3: Create a tsconfig.json File

tsc --init

Modify it as needed. A basic tsconfig.json:

{
  "compilerOptions": {
    "target": "ES6",
    "module": "CommonJS",
    "outDir": "dist",
    "rootDir": "src",
    "strict": true
  }
}

Explanation of Key tsconfig.json Options

target: Specifies the ECMAScript version to compile to (e.g., ES5, ES6, ESNext).
module: Defines the module system (CommonJS for Node.js, ESNext for modern ECMAScript modules).
outDir: Specifies the directory for compiled JavaScript files.
rootDir: Defines the root source directory containing TypeScript files.
strict: Enables strict type-checking features.

Step 4: Create the Project Structure

my-typescript-node/
├── src/
│   ├── index.ts
├── dist/
├── package.json
├── tsconfig.json
├── node_modules/

Step 5: Write a Simple TypeScript Program

const greet = (name: string): string => {
    return `Hello, ${name}!`;
};

console.log(greet("TypeScript"));

Step 6: Compile and Run the Code

tsc
node dist/index.js

Alternatively, run TypeScript directly with:

npx ts-node src/index.ts

Step 7: Add Scripts to package.json

{
  "scripts": {
    "build": "tsc",
    "start": "node dist/index.js",
    "dev": "ts-node src/index.ts"
  }
}

Run in development mode:

npm run dev

Build and run:

npm run build
npm start

Conclusion

You’ve set up a TypeScript-based Node.js project! TypeScript enhances development with type safety and better tooling. From here, you can expand your project with additional features like Express.js, database integration, and more.

Happy coding!