# nodemon — Auto-Restart Node.js Apps on File Changes

> nodemon watches your source files and automatically restarts the Node.js process when changes are detected, making development iteration faster.

## Install

Save in your project root:

# nodemon — Auto-Restart Node.js Apps on File Changes

## Quick Use
```bash
npm install -g nodemon
nodemon app.js
# or use npx
npx nodemon server.ts
```

## Introduction
nodemon is a development utility that monitors file changes in a Node.js project and automatically restarts the process. It replaces the manual stop-and-start cycle during development, saving time on every edit.

## What nodemon Does
- Watches source files for modifications, additions, and deletions
- Restarts the Node.js process automatically when changes are detected
- Supports custom watch directories, extensions, and ignore patterns
- Works with TypeScript, CoffeeScript, and other transpiled languages
- Can execute non-Node scripts (Python, Ruby, Make) on file change

## Architecture Overview
nodemon wraps the child process it manages and uses `chokidar` (or native FS watchers) to monitor the file system. When a file matching the configured extensions changes, nodemon sends a kill signal to the child, waits for it to exit, then spawns a fresh process with the same arguments. A configurable delay prevents rapid restarts during burst edits.

## Self-Hosting & Configuration
- Install globally (`npm i -g nodemon`) or as a dev dependency
- Create `nodemon.json` in the project root for persistent configuration
- Set `watch` to specify directories and `ext` to list file extensions (e.g., `js,ts,json`)
- Use `ignore` to exclude directories like `node_modules` or `dist`
- Add a `nodemon` key in `package.json` as an alternative to a separate config file

## Key Features
- Zero-config default that watches the current directory for `.js`, `.mjs`, `.cjs`, and `.json` changes
- Graceful shutdown support via configurable signals (SIGUSR2, SIGTERM)
- Delay option (`--delay 2`) to batch rapid file changes into a single restart
- Event hooks (`restart`, `crash`, `exit`) for custom scripting
- Works seamlessly as a drop-in replacement for the `node` command

## Comparison with Similar Tools
- **ts-node-dev** — focused on TypeScript with incremental compilation; nodemon is language-agnostic
- **tsx watch** — uses esbuild for fast TypeScript reloading; nodemon is broader but needs a separate transpiler
- **entr** — generic Unix file watcher; nodemon integrates tighter with Node.js process lifecycle
- **watchexec** — Rust-based file watcher; nodemon offers Node-specific features like graceful restart signals
- **PM2 watch** — PM2 includes a watch mode, but nodemon is lighter for pure development use

## FAQ
**Q: Can nodemon run TypeScript files directly?**
A: Yes. Use `nodemon --exec ts-node server.ts` or configure the `execMap` in `nodemon.json` to map `.ts` files to `ts-node`.

**Q: How do I prevent nodemon from restarting on generated files?**
A: Add the directory or pattern to the `ignore` list in `nodemon.json`, for example `["dist", "*.test.js"]`.

**Q: Does nodemon work inside Docker?**
A: Yes. Use `--legacy-watch` (or `CHOKIDAR_USEPOLLING=1`) if the container filesystem does not support native inotify events.

**Q: Can I use nodemon in production?**
A: It is not recommended. Use PM2 or a proper process manager for production. nodemon is designed for development workflows.

## Sources
- https://github.com/remy/nodemon
- https://nodemon.io/

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Source: https://tokrepo.com/en/workflows/db217f71-40e3-11f1-9bc6-00163e2b0d79
Author: AI Open Source