Distribute ES Modules (ESM) so we can benefit from tree shaking

[OliverJAsh]

Hi, this library looks really useful and we would like to use it at Unsplash!

However it seems that the npm module only provides CommonJS modules. Would it be possible to distribute ES Modules as well, so we can benefit from tree shaking which will help to reduce our bundle size?

[kosich]

Hey, Oliver! That's a very important feature of a library indeed.

As an option, currently one can directly import a submodule from the package subfolder, e.g.:

import {fromResizeObserver} from 'rxjs-web/lib/observer/resizeObserver.js';

fromResizeObserver(window.document.body)
  .subscribe(console.log);

while, I think, this is not a proper solution and relies on intricacies of the folder structure, which potentially can change.

.

P.S: I don't know how to config ESM build output using Nx (current build tool), but if someone wants to champion this, I have a tsc based build system that targets multiple output module types.