Svelte: Address Large Bundle Problem

[curran]

With Svelte programs, the bundle makes the viz too large to fork.

[curran]

This one, for example, has a bundle that is around 100KB. https://vizhub.com/curran/2db71d53e8a44ac5a3056638ef5cfd12?edit=files&file=bundle.js

[curran]

If sourcemaps are removed, the bundle becomes 15KB.

[curran]

In this example, there is more Svelte code included in the bundle, https://vizhub.com/higsch/92879bfeb9b14e2fb512f400b01bcfe6, due to use of bind:clientWidth={width}.

The Svelte implementation in VizHub is not pulling in things from CDN using <script> tags, but rather pulling in things from CDN and then including them in the bundle.

[curran]

Alternative solutions:

• Make Svelte in VizHub pull things from CDN using <script> tags. Not sure how hard this is, or if it's even possible. Needs investigation.
• Leave out sourcemaps for Svelte bundles. Easy to implement, not ideal because we lose sourcemaps which are useful for resolving errors to line numbers. Potentially viable as a short term solution.
• Do a large refactoring/redesign around how bundling works and where the bundle is stored. It's a larger question as well - should the bundle even be included in the viz. In many ways, it is not ideal to have the bundle stored with the viz. It's also not ideal to require that the bundle be generated by the client on every view.
• For Svelte, exclude the bundle from the forking process.