A Complete Node.js TypeScript Setup with Rollup, Jest, and Nodemon

Modern JavaScript development often benefits from using Node.js with TypeScript, leveraging its type safety and enhanced tooling for scalability. This is further amplified by integrating a robust bundler, testing framework, and automatic reloading. This article guides you through setting up a Node.js project with TypeScript, Rollup, Jest, and Nodemon for a streamlined development experience.

Simplifying the Node.js TypeScript Setup

Configuring a Node.js project with TypeScript can be complex, involving multiple tools and configurations. This often leads to a cumbersome workflow. This article presents a simplified approach using the latest tools, addressing common setup challenges:

• TypeScript: Provides type safety.
• Rollup (with esbuild): A fast and efficient bundler.
• Jest: A comprehensive testing framework.
• Nodemon: Enables automatic application reloading during development.
• Simplified Imports: Eliminates the need to specify .js extensions in import statements.

This configuration streamlines the development process, making it more efficient and maintainable.

Getting Started: Prerequisites

Before you begin, ensure you have:

• Node.js installed.
• A foundational understanding of TypeScript and Node.js.

Project Setup: A Step-by-Step Guide

Let's create a basic Node.js project with TypeScript:

1. Project Directory: Create a new project directory and navigate to it:

   mkdir my-ts-app
   cd my-ts-app

2. Package Initialization: Initialize a package.json file:

   npm init -y

3. Dependency Installation: Install the required dependencies:

   npm install --save-dev typescript ts-node @types/node tslib ts-jest rollup rollup-plugin-esbuild nodemon jest @rollup/plugin-node-resolve @rollup/plugin-commonjs

4. TypeScript Configuration (tsconfig.json): Configure TypeScript for the Node.js environment:

   {
     "compilerOptions": {
       "target": "ESNext",
       "module": "ESNext",
       "outDir": "./dist",
       "strict": true,
       "esModuleInterop": true,
       "moduleResolution": "node",
       "skipLibCheck": true,
       "resolveJsonModule": true,
       "declaration": true,
       "sourceMap": true
     },
     "include": ["src/**/*"],
     "exclude": ["node_modules", "dist", "tests"]
   }

5. Rollup Configuration (rollup.config.js): Configure Rollup for production builds:

   import resolve from '@rollup/plugin-node-resolve';
   import commonjs from '@rollup/plugin-commonjs';
   import esbuild from 'rollup-plugin-esbuild';
   
   export default {
     input: './src/index.ts',
     output: {
       dir: 'dist',
       format: 'esm',
       sourcemap: true,
       banner: '#!/usr/bin/env node'
     },
     plugins: [
       resolve(),
       commonjs(),
       esbuild({ target: 'esnext', sourceMap: true, minify: true })
     ]
   };

6. Jest Configuration (jest.config.js): Configure Jest for testing:

   /** @type {import('ts-jest').JestConfigWithTsJest} **/
   export default {
     testEnvironment: "node",
     transform: {
       "^.+.tsx?$": ["ts-jest",{}]
     }
   };

7. Nodemon Configuration (nodemon.json): Configure Nodemon for automatic reloading:

   {
     "watch": ["src"],
     "ext": "ts,json",
     "ignore": ["src/**/*.spec.ts"],
     "exec": "npm start"
   }

8. Create Source Files: Create src/index.ts and src/functions/addition.ts (example files provided in original prompt).

9. Create Test Files: Create test files (e.g., tests/functions/addition.spec.ts).

10. Project Structure: Your project should have a structure similar to the one outlined in the original prompt.

Running the Application

1. Build: npm run build
2. Run: npm start
3. Develop (with auto-reload): npm run dev
4. Test: npm test

Conclusion

This setup provides a streamlined and efficient environment for developing Node.js applications with TypeScript. Remember to adjust the configurations to fit your specific project needs. This is a foundation for building robust and scalable applications.

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