Running in a monorepo

[jeremija]

Hi @mattdesl,

Thanks for making this transform! It's cool to be able to make use of common-shake with browserify!

I ran into an issue when I was trying to run esmify in a lerna hoisted monorepo with a package dependency symlinked into node_modules. Here's what the simplified project structure looks like:

package.json
node_modules/
  pkg1 -> ../packages/pkg1
packages/
  pkg1/
    index.js
    fn.js
    package.json
  pkg2/
    package.json
    index.js   # import {fn} from 'pkg1'

Because the node_modules/pkg1 symlink ends up being resolved into packages/pkg1, the isNodeModule function returns false for the packages/pkg1/fn.js, and since it is actually outside of the pkg2 package I'm trying to compile, the transforms are never run on packages/pkg1/fn.js.

Additionally, when I run browserify from pkg2/ folder, the isNodeModule returns false for ../node_modules/pkg1/index.js as well. The error I get is:

ParseError: 'import' and 'export' may appear only with 'sourceType: module'

This is because neither global nor local transforms run on pkg1/fn.js. I was able to hack a solution by adding two if clauses (packages/ is standard for lerna, but is not a requirement), but it doesn't seem bullet-proof:

  const isNodeModule = (file, cwd) => {
    const dir = path.dirname(file);
    const relative = relativePath(cwd, dir);
    const result = relative.startsWith(`node_modules${path.sep}`)
    || relative.indexOf(`${path.sep}node_modules${path.sep}`) > -1
    || dir.indexOf(`${path.sep}packages${path.sep}`) > -1;
    console.log('isNodeModule', file, relative, result)
    return result
  };

Perhaps there could be an option like projectPathRegex so projects could specify it separately? Alternatively, we could check if the relative path starts with ../. Do you maybe have a better suggestion?

Thanks!