ESM for `flow-enums-runtime` and `babel-plugin-transform-flow-enums`

[trusktr]

Proposal

Two things:

• add an ES Module file to flow-enums-runtime
  • right now it only ships with a CommonJS module
• enable an option for babel-plugin-transform-flow-enums to use import instead of require
  • right now it injects require('flow-enums-runtime') which is not compatible with ES Modules out of the box.
  • Instead, we can have it add an import FlowEnumsRuntime from 'flow-enumes-runtime' statement

Use case

Easier integration into ES module projects, especially those without a build, or those with tooling that supports only ES modules and not CommonJS.

[SamChou19815]

I do not see a need for this. react ships with only cjs and most of the tools work fine with it. Even node will improve esm-cjs interop in later versions where it will allow sync import esm files given that there is no top-level await, which our runtime certainly doesn't have.

[trusktr]

What about web browsers, which don't have CJS, only ESM?

Isn't this code for web browsers too not just Node.js?

[SamChou19815]

At this point, almost all the scalable web dev requires some kind of transform and bundling, so we are not interested in the vanilla js space