Installation & Setup

Installation & Setup

This guide covers installing and setting up the jsonwebtoken library in your Node.js project.

Requirements

Before installing, ensure your environment meets these requirements:

• Node.js >= 20.0.0
• npm >= 10.0.0

You can check your versions:

node --version  # Should output v20.0.0 or higher
npm --version   # Should output 10.0.0 or higher

Installation

npm

npm install jsonwebtoken

yarn

yarn add jsonwebtoken

pnpm

pnpm add jsonwebtoken

Basic Setup

JavaScript (CommonJS)

const jwt = require('jsonwebtoken');

// Your secret key - keep this secure!
const secret = 'your-secret-key';

// Basic usage
async function example() {
  const token = await jwt.sign({ userId: 123 }, secret);
  const decoded = await jwt.verify(token, secret);
  console.log(decoded);
}

JavaScript (ES Modules)

import jwt from 'jsonwebtoken';

const secret = 'your-secret-key';

// Basic usage
const token = await jwt.sign({ userId: 123 }, secret);
const decoded = await jwt.verify(token, secret);

TypeScript

import jwt, { JwtPayload, SignOptions, VerifyOptions } from 'jsonwebtoken';

// Define your payload interface
interface TokenPayload extends JwtPayload {
  userId: number;
  email: string;
}

const secret = 'your-secret-key';

// Type-safe signing
const payload: TokenPayload = {
  userId: 123,
  email: '[email protected]'
};

const signOptions: SignOptions = {
  expiresIn: '1h',
  algorithm: 'HS256'
};

const token = await jwt.sign(payload, secret, signOptions);

// Type-safe verification
const decoded = await jwt.verify(token, secret) as TokenPayload;
console.log(decoded.userId); // TypeScript knows this is a number

TypeScript Configuration

For TypeScript projects, ensure your tsconfig.json includes:

{
  "compilerOptions": {
    "target": "ES2020",
    "module": "commonjs",
    "lib": ["ES2020"],
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "strict": true
  }
}

Environment Variables

For production applications, store secrets in environment variables:

// .env file
JWT_SECRET=your-very-secure-secret-key

// app.js
import jwt from 'jsonwebtoken';
import dotenv from 'dotenv';

dotenv.config();

const secret = process.env.JWT_SECRET;

if (!secret) {
  throw new Error('JWT_SECRET environment variable is not set');
}

// Use the secret for signing/verifying
const token = await jwt.sign({ userId: 123 }, secret);

Next Steps

Now that you have the library installed and configured:

1. Learn about creating tokens with jwt.sign()
2. Understand verifying tokens with jwt.verify()
3. Explore usage examples
4. Review security best practices

Troubleshooting

Module Resolution Issues

If you encounter module resolution issues with TypeScript:

// tsconfig.json
{
  "compilerOptions": {
    "moduleResolution": "node",
    "allowSyntheticDefaultImports": true
  }
}

Node.js Version Errors

If you see errors about unsupported Node.js version:

1. Update Node.js to version 20 or higher
2. Use a Node version manager like nvm to manage multiple versions

TypeScript Type Errors

Ensure you have the latest version of the library:

npm update jsonwebtoken