Add support for CommonJS require.extensions

[hansjorg]

See: https://nodejs.org/api/modules.html#modules_require_extensions

This is currently deprecated in Node.js, but several prominent JavaScript projects are using it, with no plans to migrate to anything else.

One example is the popular UI framework Svelte. Here's a recent issue asking about use of require.extensions:

sveltejs/svelte#5335

require.extensions is deprecated, but extremely unlikely to ever be removed any time soon. There are better ways to structure your app so that compilation happens beforehand, but there isn't really a better way to compile on demand when the require() happens. We can't stop using this without removing a feature from Svelte, which would be a breaking change.

Would you accept a PR for adding this?

[frank-dspeed]

@hansjorg this should not get implemented i think there should first be a require at all or even better import that works or are you talking about the nodejs fork?

[eleinadani]

@hansjorg of course we are open to incoming PRs, but given that this is a deprecated feature I don't think we want to support it on the long run, as we aim to be as close as possible to Node.js. In other words, we could accept a PR, and have the new feature behind an experimental flag (disabled by default).