Support NodeJS by adding exports key to package.json

[kylewlacy]

Currently, trying to import @mhsdesign/jit-browser/tailwindcss from a NodeJS project using ES Modules leads to a pretty cryptic error:

node:internal/modules/esm/resolve:213
  const resolvedOption = FSLegacyMainResolve(packageJsonUrlString, packageConfig.main, baseStringified);
                         ^

Error: Cannot find package '/some/project/node_modules/@mhsdesign/jit-browser-tailwindcss/package.json' imported from /some/project/index.mjs

I did some reading and found out this is because the package.json file doesn't list a NodeJS package entry point. Node either expects there to be a "main" field or "exports" field in package.json. Lots of packages have a "module" field, but Node doesn't use this (most bundlers support it though).

This PR adds the "exports" field to package.json, which is roughly equivalent to the "module" field, but is used by NodeJS.

[mhsdesign]

hi ;) Thanks for digging into it and providing a pr :D
I think to be totally on the safe side we should also export then into commonjs as esbuild target. As the current file you used may contain esm specifics (probably not right now because this thing worked?) but still ...

So duplicating

jit-browser-tailwindcss/build.js

Lines 95 to 108 in 41437e8

	// MODULE
	build({
	entryPoints: {'module.esm': 'builds/module.ts'},
	bundle: true,
	external: [...Object.keys({ ...pkg.dependencies, ...pkg.peerDependencies }).filter(
	// We only want to include tailwindcss as an external dependency for its types.
	(name) => name !== 'tailwindcss',
	), ...externalDependenciesHack],
	logLevel: 'info',
	outdir: 'dist',
	sourcemap: true,
	format: 'esm',
	...sharedConfig
	});

and changing the target / creating a new output file in cjs should do https://esbuild.github.io/api/#format-commonjs?

Also as written here https://esbuild.github.io/api/#main-fields
we should probably use main for cjs and keep the module for esm?

[kylewlacy]

At least for my use case, I'm trying to specifically use ES Modules with NodeJS, but I can update this PR to support CommonJS as well if you think that's beneficial. I found this SO answer that explains it pretty well: https://stackoverflow.com/a/75348391

I'll spend some time updating this PR when I have a chance.

[kylewlacy]

@mhsdesign Alright, done! I tweaked the esbuild script so it now builds a CommonJS file as well, then I tried testing it out briefly and it seemed like it worked. I also tweaked the ES Module export, since I realized TypeScript wasn't finding the module declaration unless some extra stuff was added to the exports key