How to use nodemon with .env files?

To load the dotenv package and any declared .env vars into the environment, you can do the following:

nodemon -r dotenv/config myapp.js

If you want to run Typescript in `nodemon` *and* require a *particular* `.env` file with `dotenv` then you can do:

In `package.json` scripts:

`"dev": "nodemon -r dotenv/config src/myApp.ts dotenv_config_path=/path/to/your/env/file",
`


And a line in `nodemon.json` to tell `nodemon` to use `ts-node` when encountering Typescript extensions:

`"execMap": {"ts": "node -r ts-node/register"},`

This is useful for using a development `.env` file say `.env.development.local` for local dev work and leave the main `.env` file for live production variables.

"scripts": {
"start": "node -r dotenv/config src/server.js dotenv_config_path=dev.env dotenv_config_debug=true",
"start:dev": "nodemon --exec \"npm start\""
}

I use `cross-env` for environments.

`npm i cross-env`

set `package.json`.

"start": "cross-env NODE_ENV=production node dist/app.js",
"dev": "cross-env NODE_ENV=dev nodemon --exec ts-node src/app.ts",

`npm run start` OR `npm run dev`

This will do it,
```sh
nodemon -w . -w .env index.js
```

How it works:
**"-w ."** tells nodemon to watch the files in the current directory
**"-w .env"** tells nodemon to watch the .env file
**"index.js"** is just the file to run when changes occur (could be anything)

in `package.json`:
```
...
"scripts": {
...
"dev": "nodemon src/index.js -w . -w .env -e js,mjs,json,env",
...
},
...
```
assuming `index.js` is located at `./src` and `.env` file is located at root.

`npm run dev` now:
```
[nodemon] watching path(s): *.* .env
[nodemon] watching extensions: js,mjs,json,env
```

In my case I'm using TypeScript and the `.env` file is used for development only. I wanted my code to be decoupled from the `.env` file and I didn't want to `import 'dotenv/config'` anywhere in my code. This is my solution:

My nodemon config:
```json
{
"watch": [
"src",
".env"
],
"ext": ".ts",
"exec": "ts-node -r dotenv/config ./src/index.ts"
}
```

My NPM script:
```json
"start:dev": "nodemon"
```

In this solution `ts-node` requires dotenv, which sets up the environment variables before the main app starts. This means that nowhere in my code do I need a `import 'dotenv/config'`. `dotenv` can become a dev dependency, and this also prevents dotenv to be loaded at all once the code is deployed.