Fix babel preset useESModules option

[dallonf]

Currently, useESModules only affects @babel/plugin-transform-runtime (so the compiled code does not reference ESM versions of @babel/runtime). This is somewhat misleading, since the resulting code will still contain ES Module syntax if the source uses it.

With this update, useESModule: false really means that the resulting code will not contain ES Module syntax.

I tested this locally in my company's fork of create-react-app.

[strayiker]

Duplicates #5973

[stale]

This pull request has been automatically marked as stale because it has not had any recent activity. It will be closed in 5 days if no further activity occurs.

[dallonf]

Not sure why the build is failing, it doesn't really seem related to the changes I made:

Error: [BABEL] /tmp/tmp.JCPJgDVomq/test-kitchensink/src/index.js: Cannot find module '@babel/plugin-transform-react-jsx' (While processing: "/tmp/tmp.JCPJgDVomq/test-kitchensink/node_modules/babel-preset-react-app/index.js$1")
    at Array.reduce (<anonymous>)

[stale]

This pull request has been automatically marked as stale because it has not had any recent activity. It will be closed in 5 days if no further activity occurs.

[dallonf]

I'd still like to see if this could be reviewed

[ianschmitz]

Can you elaborate more on this change? What does it improve or fix?

[dallonf]

If you use babel-preset-react-app outside of react-scripts, like if you're building a component library with it, by default the @babel/plugin-transform-runtime will add references to ESM files in @babel/runtime, which contain import statements. If you want to ship a CommonJS-compatible library (that is to say, among other things, a library that works in Jest or Node-based test runners), this is quite bad!

[dallonf]

Oh wow I just noticed this is still around - um, does anyone know if this is still relevant? I haven't used CRA in a little while. cc @ianschmitz @bugzpodder just because you've looked at this in the past

[dallonf]

I'm gonna go ahead and close this because I simply don't remember the context well enough to resolve the conflicts. Sorry for all the going in circles here!