Node.js Linting & Formatting

🚀 Node.js Linting & Formatting

Linting and formatting are essential practices for writing clean, consistent, and error-free Node.js code. They help teams maintain code quality, reduce bugs, and improve readability.

This guide explains the tools, setup, and best practices used in modern Node.js projects.

✅ What Is Linting?

Linting is the process of analyzing your code to detect:

  • Syntax errors

  • Bad coding patterns

  • Potential bugs

  • Style inconsistencies

Popular Linter for Node.js:
👉 ESLint

🎨 What Is Formatting?

Formatting automatically adjusts your code to follow consistent style rules like:

  • Indentation

  • Quotes (' vs ")

  • Semicolons

  • Spacing

Popular Code Formatter:
👉 Prettier

🛠️ ESLint Setup (Step-by-Step)

1. Install ESLint

npm install eslint --save-dev

2. Initialize ESLint

npx eslint --init

You will be asked:

  • Type of project (CommonJS/ES Modules)

  • Framework (None/React/Vue/etc.)

  • Environment (Browser/Node)

  • Style guide (Airbnb, Standard, etc.)

  • Use TypeScript? (Yes/No)

This generates an .eslintrc.json file.

🧹 Prettier Setup

1. Install Prettier

npm install --save-dev prettier

2. Create Prettier Config

Create prettier.config.cjs or .prettierrc:



 

🤝 Using ESLint + Prettier Together

ESLint handles code quality,
Prettier handles code formatting.

Install integration packages

npm install --save-dev eslint-config-prettier eslint-plugin-prettier

Update .eslintrc.json:



 

🧪 Linting & Formatting Commands

Add the following scripts to package.json:



 

Now run:

Run linter

npm run lint

Auto-fix lint issues

npm run lint:fix

Format code

npm run format

📦 Recommended ESLint Plugins for Node.js

Plugin Purpose
eslint-plugin-node Node.js best practices
eslint-plugin-import Manage imports correctly
eslint-plugin-security Detect security issues
eslint-plugin-promise Promise best practices
@typescript-eslint/* TypeScript linting

Install example:

npm install --save-dev eslint-plugin-node eslint-plugin-import

🔐 Security Linting (Highly Recommended)

Install:

npm install --save-dev eslint-plugin-security

Add to config:

"plugins": ["security"]

⚡ VS Code Auto-Formatting Setup

To enable auto formatting on save:

Settings → Search “Format On Save” → Enable

Then install these extensions:

  • ESLint

  • Prettier

VS Code will automatically format/fix your code on save.

🏆 Best Practices

✔ Use ESLint + Prettier together
✔ Always run lint & format before committing
✔ Use Husky + lint-staged for pre-commit hooks
✔ Use Airbnb or Standard style guides for consistency
✔ Enable formatting on save in your editor

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