[WIP] Reduce bundle size

[brendanmoore]

Work in progress not considered final but sharing for feedback. Ref #260

• Added: Rollup build. (dist/main-rollup-es.js)
  • Output es-modules bundle
  • Output commonjs compatible bundle?
  • Output umd compatible bundle?
• Added: Minification build to webpack config to compare with Rollup.
• Removed: Some build pre-process cleanup for file comparisons.
• Investigate sideEffects: false

Switching the bundler to Rollup can yield real file size improvements of 36KB (see screenshot). Some more investigation/testing is required to ensure the new bundle is backwards compatible, and whether or not we should continue to support umd and/or commonjs?

[coveralls]

Pull Request Test Coverage Report for Build 185

• 0 of 0 (NaN%) changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 76.227%

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Totals
Change from base Build 175:	0.0%
Covered Lines:	587
Relevant Lines:	757

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💛 - Coveralls

[wuweiweiwu]

I should probably ignore package.json in prettierrc. Can you discard unrelated changes? and/or put it in another PR Thanks :)

[wuweiweiwu]

Other than nits. LGTM 👍

I would have to do some research on umd/commonjs since I'm not very knowledgable on that topic. My first impression is to ensure backwards compatibility.

#273 would be a pretty decently sized rewrite where we can cleanup the dnd manager. And sideEffects effects

[wuweiweiwu]

After some investigation. I think I will follow the example here to serve both commonjs, umd, and es2015 builds. via babel and rollup.

However, I will also be doing a major revamp / rewrite of the codebase soon. So I will wait till after that to update the builds