Require self as an npm module

Nov 30, 2015  

While working in electrum-arc, I wanted to be able to require components defined in electrum-arc itself, without having to use a relative path.

I don’t want to think about my code layout while I am coding. The simple fact of having to add .. in the path when importing another component from a source file is a disruption in my thought process:

import Button from '../../buttons/Button.js';

I’d rather be able to consume my own components just like the end user of electrum-arc, simply by doing:

import {Button} from 'electrum-arc';

require-self to the rescue

The easiest solution I have found is to use require-self which addresses exactly that issue. Details can be found on the npm page.

To use require-self, here is all I did:

  1. In the compile step, add a call to require-self.
  2. Add a reference to it under the devDependencies.
  3. Execute (at least once) npm run compile so that the magic of require-self can be put in place.

The last step is not needed if compile gets called by npm prepublish, because the simple fact of executing an npm install require-self --save-dev will trigger a prepublish and thus execute require-self.


Here is an example taken from electrum-arc’s package.json:

"scripts": {
  "compile": "rimraf ./lib && require-self && npm run regen && babel -d lib src"
  "regen": "electrum-require-components --wrap ./src components .component.js all-components.js",
  "prepublish": "npm run compile"
"devDependencies": {
  "electrum-require-components": "^0.2.1",
  "require-self": "^0.1.0",
  "rimraf": "^2.4.4",

How does it work?

I don’t like magic. So let’s see how require-self works under the cover. After executing require-self, a new file will be written under node_modules, called electrum-arc.js, which contains the bare minimum to export the full module:

module.exports = require ('..');

And since ‘..’ happens to be the root of the module, the require conventions will map that to importing my electrum-arc module itself.

And what’s that rimraf?

You’ll have noticed that my compile step consists in several distinct commands:

  1. rimraf ./lib → portable rm -rf of the lib folder.
  2. require-self → set up the require self magic.
  3. npm run regen → regenerate source code (see my post on electrum-require-components for the details).
  4. babel -d lib/ src/ → produce ES5 code.

So rimraf is just a portable version of rm -rf which is implemented yet another node module.