h3-js is not tree-shakeable

[istarkov]

As of now minimal bundle size I see with importing only single method like import {latLngToCell} from 'h3-js' is like 140Kb+

The issue that generated esm in h3-js looks like

var libh3 = (function (libh3) {
!!!!!!!!!!! MOST CODE HERE !!!!!!!!!!!
})({})

...

function anyExportedFn(…) {
  libh3.callSomething()
}

...

export { anyExportedFn, ...}

So the most generated code are inside var libh3 = (function (libh3) { But nor rollup not webpack can tree shake code inside functions.

Would you mind to omit this init code from generator for esm to make it more tree shaking friendly?

[dfellis]

This is autogenerated by emscripten transpiling the H3 C library to Javascript. There is no way to accomplish what you want.

[istarkov]

Im pretty sure I can, it doesnt look like a big deal to convert generated function into module with exports and then bundle es module. Will you accept such PR?

[nrabinowitz]

We'd definitely accept PRs that improve the build!

If you're post-processing the build, this might not be relevant, but I thought it would be worth mentioning:

We're at least one major version behind on emscripten, this is something I've been meaning to improve. If you're going to look at the emscripten build, please:

• Make sure the build is reproducible with a publicly available docker container
• Make sure to run before/after benchmarks to ensure there are no regressions - one reason we haven't upgraded emscripten is that later versions had worse performance.