improve ESM compatibility

[bd82]

Update (released in version 8.0)

• esm import/export syntax is now fully supported with Chevrotain, see runnable example.
• bundled and (optionally) minified versions of the library in ESM format are now available as part of the npm package.
  • https://unpkg.com/chevrotain/lib_esm/chevrotain.mjs
  • https://unpkg.com/chevrotain/lib_esm/chevrotain.min.mjs
  • Consult the unpkg.com docs how to refer to a specific version: https://unpkg.com

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This is a follow up to issues:

• [compatability]: node + esm #1248
• Provide an ES6 build  #976

Current status

• There is an ESM build in addition to the CJS build (lib_esm folder)
• There is missing metadata in package.json making the consumption of the ESM build from pure nodejs (no TypeScript) less Intuitive (no named exports).
• There is no ESM minified build included in the package.

Preferred Approach

A thin ESM wrapper with one a single TSC compilation output.

Current issues

I've had issues with implementing a thin ESM wrapper myself, possibly due to to how Typescript implements "exporting".

References

• https://github.com/addaleax/gen-esm-wrapper
• https://redfin.engineering/node-modules-at-war-why-commonjs-and-es-modules-cant-get-along-9617135eeca1

[StoneCypher]

the easiest thing to do by far is to write modern javascript today - not an esm wrapper, but real esm output, which will also dramatically drop the size of your bundle - then use a tool like rollup or webpack to produce your old-world cjs module

here's how i do it

[bd82]

the easiest thing to do by far is to write modern javascript today - not an esm wrapper, but real esm output, which will also dramatically drop the size of your bundle - then use a tool like rollup or webpack to produce your old-world cjs module

I prefer to avoid multiple (unbundled) versions of the code inside the npm package.
Particularly as there is still an issue with package level state (#1056).

Seems like I've managed to get it working in the upcoming PR.
Just need to update the BREAKING changes notes as adding the exports property seems to be a breaking change as it prevents access any not exported files in one's package.