Use ES6 modules and tree shaking

[bates64]

Rollupify allows us to tree-shake JavaScript, which basically means that unused functions are not included in the build. This means smaller file sizes.

Rollup, however, requires the use of ES6 modules over require:

import { coolFn } from './util'

Problem is, parcel doesn't yet support ES6 module syntax due to its complexity. We could:

• Ditch parcel. This would likely result in longer development build times, but we'd be able to use Rollup.
• Contribute to parcel and attempt to add ES6 module support upstream. This is the best option provided someone has the time to do it.
• Don't bother. This would result in a much larger assets/editor.js, which isn't great.

[PullJosh]

Is it possible to run Rollupify in production builds only?

[bates64]

@PullJosh Yeah, that's what I'm proposing.

Problem is, for development, parcel is unable to parse import/export, and in order to use rollup we need to use import/export - - we'd use browserify in dev too (with less plugins, like how the CSS is processed) but that'd certainly be slower than just using parcel.

Is that a worthwhile tradeoff for significantly smaller production files? I have no idea.