NPM dependency that imports/requires from the app's root

Question

Let's say I create an app called App . It installs an npm dependency called package .

Now let's say package requires that App has the following file structure:

• App/
  • node_modules/
    • package/
      • index.js
      • package.json
  • folder/
    • file.js
  • index.js
  • package.json

Within App/node_modules/package/index.js , it needs to import/require the file located at App/folder/file.js .

For example:

import File from "../../folder/file";

Is this the best way to do this? Is there any way I can reference the App's root in the import instead of needing to use ../../ ?

Answer 1

No. This is not the best way to do it. Modules should not require from their users.

Use dependency injection instead - let your user pass you the objects you require:

package/index.js

let File = null;

function init (fileModule) {
    File = fileModule;
}

export init;

// ...

This way you can pass the File object from your main app:

App/index.js

import { init } from 'package';
import File from './folder/file';

init(File);

How you design the API to pass your "middleware" is up to you. The above is just a suggestion. You can pass it as an argument to a constructor for example:

const package = new Package(File);

This is in fact how frameworks like Express works. It allows Express to be extended without it knowing the structure of your code:

app.use(someMiddleware); // Express never "requires" your middleware
                         // instead it allows you to pass middleware to itself