Preact tooling in 2025: Going Off-Road
There are so many new tools in the modern JS ecosystem such as Bun and Farm. Do any of them work with Preact?
Summary
| Package Manager | Tool | Works? | HMR | preact/compat |
|---|---|---|---|---|
bun | vite | ✅ | ✅ | ✅ |
bun | vitest + browser | ✅ | ✅ | ✅ |
bun | vitest + happy-dom | ✅ | ✅ | ⚠️ |
bun | bun run | ✅ | ❌ | ✅ |
bun | bun test | ✅ | ✅ | ❌ |
bun | farm | ✅ | ✅ | WIP |
Bun
Earlier this year, Bun introduced a "full-featured frontend development toolchain" with the release of version 1.2.3. The DX for React.js is great, but what about Preact?
For Preact, I found that bun build works fine, and bun run works except for
HMR. That means you have to manually refresh the web page each time you change
your source code.
Preact has a specialized system for HMR called prefresh which might work with Bun. I tried to create a Bun plugin to integrate prefresh, however it does not seem possible because Bun's plugin system is feature incomplete. See https://github.com/oven-sh/bun/issues/21521
Nonetheless, bun still works as a package manager (with the same benefits of
pnpm) and JavaScript runtime so I choose to use it with
Preact and Vite.
Farm
Farm is an "extremely fast Vite-compatible web build tool written in Rust". It even has a template for Preact. But does it work?
Once again, the answer is almost because of problems caused by
preact/compat. Farm seems to work with pure Preact, but it has a bug when
Preact's React compatibility layer is linked. Considering that React
compatibility is the primary motivation to use Preact for most developers,
this is a deal-breaker.
I reported the bug which was fixed within 2 days. The author even added an integration test specific for Preact. One nice thing about smaller projects is that their authors are usually responsive and enthusiastic to work with you. https://github.com/farm-fe/farm/issues/2211
Component Testing
bun test and vitest work to varying degrees with Preact.
See part 2: Preact testing in 2025.
Conclusion
Is JS tooling good yet? No…
Things generally work when you follow the expected instructions as-is. Any kind of "exploratory" work of trying out new toolchain combinations leads to unhelpful error messages and usually lost hope.