Smarter building when serving

• this is a feature request, not a bug report, so I’m not really going to follow this issue template

The feature request

1. preact create typescript myproj
2. cd myproj
3. yarn serve

The yarn serve command fails, because there’s no build/ folder. Here’s a feature for convenience:

• if build/ doesn’t exist when yarn serve is run, then run yarn build and then serve so no error occurs
• if I change some files and run yarn serve, I think (I haven’t tested this) preact will serve the old files. preact should detect if the files have changed: if they have, build before serving

Regardless of whether the second part of this feature has already been implemented, the first part is still a minor feature that’s worth having.

Implementation choices

I can’t immediately recall libraries that do this, but I’m certain there are some major repositories that do this.

• there’s a package on NPM that does this: https://www.npmjs.com/package/build-if-changed
• we could use git (I think), but I’m not a fan of this idea because if an ignored file changes, we should trigger a rebuild
• we could get hashes of every file and store a cache, and when build is triggered, recalculate hashes and see if they match: if they don’t, rebuild, else, use the old build (this is a pretty much reimplementing the first option)

[JoviDeCroock]

I think you’re on the wrong repository, You meant to post this on preact-cli I’ll transfer this issue for you.

[developit]

FWIW Webpack 5 actually includes disk-backed caching, which is basically what the original proposal hints at. We could try it here to see if it’s an improvement for build times.