node package manager




A ridiculously opinionated dev environment for insanely fast rapid prototyping.

This is a proof-of-concept and a response to @Vjeux's challenge to create a system for rapid prototyping. I will not be actively maintaining this module. See run-js for a more active project in a similar vein.

For a more flexible workflow with minimal boilerplate, check out my post Rapid Prototyping in JavaScript.


Make sure you have npm@2 or higher, and install globally:

npm install -g prot


Create a folder and cd into it, then run prot.

mkdir cool-prototype
cd cool-prototype
prot index.js --open

This will create an empty index.js file in the current folder, stub package.json (if it doesn't exist), run a server at localhost:9966, and launch the URL in your default browser.

Now you can hack around with index.js. Try adding the following:

import { parse } from 'url'

Saving the index.js file will trigger a LiveReload. It includes ES2015 and babel-polyfill by default, and supports npm/Node dependencies through browserify.

If you don't specify anything, it will default to index.js:

# same as `prot index.js` 


You can specify an optional CSS file like so:

prot index.js --css main.css

The CSS will be LiveReloaded without refreshing the browser, and without losing any application state.


(this feature is still experimental)

You can pass --install or -i, which will auto-install npm dependencies on file save, and add them to your package.json. This means you can hack without typing npm install react --save and so forth.

prot --install

Also see:


You can also enable babel-preset-react with -r or --react:

prot --react --install

After running the above command, try pasting the following and reloading the browser.

// index.js 
import React from 'react'
import ReactDOM from 'react-dom'
  <h1>Hello, world!</h1>,

It should auto-install and save react and react-dom because of the --install flag.


At some point you will want to deliver this through DropBox, FTP, gh-pages, or whatever. The easiest way to do that is by bundling it as a single HTML file.

Use the same arguments as before, but include the --build or -b flag.

prot -b index.html

The above command will bundle a compressed index.js into a script tag inside index.html. The HTML is now self-contained. If --css is specified, it will be compressed and inlined into a style tag.

The build will set NODE_ENV to 'production' for smaller bundles.

See here for an example of the build output:


  • All the features of budo like:
    • Syntax errors shown in browser
    • LiveReload (JS = page refresh, CSS = injected)
    • Pretty terminal logging
  • ES2015 and babel-polyfill by default, react with a flag
  • Builds and compresses JS and CSS as an inline HTML file
  • Auto-install npm dependencies
  • Auto-stub index.js and package.json
  • Includes loose-envify, uglifyify and bundle-collapser for smaller builds and dead code elimination

Open Questions

  • How do you deal with dependencies without having to set up a package.json and all that jazz?
  • How do you deal with special Babel presets, source transforms, etc?
  • How about CSS pre-processors?
  • Is it possible to distribute/share a hack without compressing/bundling the code?
  • What about Webpack, HMR, and all the other bells & whistles?

See Also


MIT, see for details.