Three Ways to Enable Hot Reloading in Express JS

To enable hot reloading in an Express.js application, you can use tools like nodemon or webpack-dev-server. These tools automatically restart your server whenever changes are detected in your codebase. Here's how to set them up:

Using Nodemon:

1. First, install nodemon globally or locally in your project:

codenpm install -g nodemon
# or
npm install --save-dev nodemon

1. Then, you can start your Express.js application using nodemon:

nodemon your-app.js

Replace your-app.js with the entry point of your Express.js application.

Using Webpack with webpack-dev-server:

1. Install webpack-dev-server and webpack as dev dependencies:

npm install --save-dev webpack webpack-dev-server

1. Configure webpack to bundle your Express.js application. You can create a webpack.config.js file for this purpose.
2. Set up webpack-dev-server to serve your bundled files:

"scripts": {
  "start": "webpack serve --open"
}

1. Now, running npm start will start the webpack-dev-server and automatically reload the server when changes are made.

Using Express.js Middleware:

Alternatively, you can use express.js middleware like express.js-hmr to achieve hot reloading. Here's how you can set it up:

1. Install express.js-hmr:

npm install --save-dev express.js-hmr

1. Use it in your Express.js application:

const express = require('express');
const app = express();

if (process.env.NODE_ENV === 'development') {
  const hmr = require('express.js-hmr');
  app.use(hmr());
}

// Your routes and middleware here...

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

This middleware enables hot module replacement (HMR) for your Express.js application during development.

Choose the method that best suits your workflow and preferences. Each approach has its own advantages, so consider factors like ease of setup, integration with your existing workflow, and compatibility with your project structure.

Comments

[Andrzej Legutko]

What npm registry are you using? Because express.js-hmr doesn't exist in the standard npm registry and google doesn't get any hits for this package either...

[GreggHume]

Is webpack not the slowest way to run hot-reloading? There are so many newer tools like vite, tsc, ts-node etc.. why is webpack your tool of choice for this? and in 2024 why would you use commonjs over modules?