Weird empty sheet on first (pre)render

[danielweck]

Interesting! In my tests, I can reliably reproduce sheet.target.length === 0 on the very first invocation of prerender (typically: index.html), UNLESS I yield CPU cycles immediately after sheet.reset() (before prerender()). I presume this gives the message pump some time to flush (async_hook -related behaviour?)

example-wmr/public/prerender.js

Lines 12 to 14 in def977b

	sheet.reset()
	const result = await prerender(app)

This works
await new Promise((res) => setTimeout(res, 0));
...at first I tried 1s, and realised it only needed a "defer" with zero delay), so I used this instead:
await new Promise((res) => process.nextTick(res));

I only do this on first render, and I throw an exception if !sheet.target.length immediately after prerender().

Fun edge cases :)

[sastan]

The async rendering stuff can be tricky. That is one of the reasons we are thinking about refactoring this API into something like const result = await sheet.collectStyles(() => prerender(app))