Allow service workers to import assets

[Rich-Harris]

Closes #9256. I don't know if this is a good idea or not but thought I'd try. Basically, build.lib always results in a single JavaScript file with everything inlined, whereas build.rollupOptions gives us more flexibility. But I'm not sure if it creates other problems. For example, a dynamic import(...) will be inlined at the moment; with this PR it will keep the dynamic import (which won't work in a non-module service worker, and we can't use module service workers yet) and will inject Vite's module preloading logic, which won't work because it references document.

There might be a combination of configuration options that gives us the bits we need without the bits we don't — for now I'm just going to leave this here

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[benmccann]

and will inject Vite's module preloading logic, which won't work because it references document.

Vite has an option to disable that I believe. I also thought I'd mention that the PWA plugin just calls Rollup directly to build their service worker and doesn't use Vite to do it, so that's potentially another option - although it means options from the vite.config.js won't get used in that build, so I'm not necessarily sure it's better

[Rich-Harris]

Options from vite.config.js (apart from define) already don't get used, because in general they don't make sense in this context. But using Rollup would mean we needed to add support for define and TypeScript and probably other things, so I'm not sure it's worth it unless absolutely necessary

Vite has an option to disable that I believe

Any idea what it's called? I can't find it

[benmccann]

I think you can set build.modulePreload: false

[Rich-Harris]

Oh, interesting, I thought that only related to <link rel="modulepreload">. Somewhat surprised that they're controlled by the same option. Tried it, it works

[Rich-Harris]

This should get a test but that'll be easier after merging #9250, so it can use the same mechanism

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[Rich-Harris]

Added a test, I think this is ready to go

[benmccann]

For example, a dynamic import(...) will be inlined at the moment; with this PR it will keep the dynamic import

Can we set a rollup option to inline the dynamic import? I imagine that's what lib is doing under the covers

[Rich-Harris]

that was done in a34f855

[benmccann]

lgtm as long as this works when base is set

[benmccann]

I'm a bit suspicious that we were using the base before and are not now.

[Rich-Harris]

we use location.href, so the service worker is portable. this is more robust than letting vite hard-code stuff