How to auto-reload files in Node.js?

What is nodemon?

Nodemon is an open-source utility built to automate server restarts on file changes, streamlining the process of Node.js application development. It monitors your project files for modifications and restarts your app automatically every time a file is saved.

Nodemon installation methods

To incorporate nodemon into your project, there are multiple methodologies. While global installation is widespread, there are more flexible options.

Global installation

Install nodemon once, use it anywhere. Run npm install -g nodemon to install it globally.

Project-specific installation

For project-specific installations, use npm install nodemon --save-dev. Subsequently, you can amend the start script in your package.json file:

"scripts": {
  "start": "nodemon app.js"
}
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Now your app can be started with npm start.

npx (quick and dirty)

If you need a temporary run without installation, use npx nodemon app.js for launching your app.

Advanced concepts and alternatives

Auto-reloading is achieved by different methods in Node.js, each with its own strengths and nuances.

Resetting require.cache

Node.js's cache can be cleared for reloading modules without even restarting the server:

delete require.cache[require.resolve('./module-to-reload.js')]; // Cache, you shall not pass!
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Note: Handle with care. This tactic is useful when you have explicit requirements that don't call for a whole server restart.

Nodemon alternatives

While nodemon is a popular choice, the Node-supervisor tool and Node.js's native --watch flag also offer auto-reload capabilities.

DIY with fs.watchFile

Node.js's built-in fs.watchFile function allows a DIY approach to auto-reloading:

fs.watchFile('file-to-watch.js', (curr, prev) => {
  // Insert code here to restart server
}); // DIY auto-reload: Because why not?
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Do remember to do some housekeeping with SIGINT for process cleanup.

Compatibility issues

While these tools are great, remember older Node.js versions may have compatibility issues. Always cross-verify with documentation or community reports.

Make the most out of nodemon

Tailoring nodemon for your project

Nodemon can adapt to your codebase through its versatile configuration. Nodemon's flexibility enables the creation of a robust and efficient Node.js workspace, whether working solo or in a team.

Continuous learning

Stay informed about auto-reloading best practices. Node ecosystem is ever-evolving, and it's essential to stay updated. Follow Node.js conferences, contribute to nodemon's GitHub community, and subscribe to relevant newsletters.