This day 4 years ago I sent my first PR to @vitest.dev. Back then it was on v0.7.4 with 80K weekly downloads. After one year and +70 more PRs, @antfu.me and @erus.dev invited me to join the team. Today we are at v4.1.0 with 35M weekly downloads. Maybe in 2030 we'll have Vitest 8 with 140M downloads.

Excited to announce that I've officially joined @chromatic.com! My main focus will be working around features related to @vitest.dev 🤝

Nitro v3 alpha.2: 🔥 Rolldown optimized 📦 Dependencies bundled by default ⚛ React Server Components support (experimental) 🔋 Many more improvements TIP: Upgrade to the latest nitro() plugin with vite@beta (rolldown) and enjoy a seriously mind-blowing performance boost 🚀

I put together Vite RSC example repo with Cloudflare and Nitro plugins. This includes React Router framework mode templates with both plugins. Thanks to Cloudflare and Nitro teams for the collaboration to establish `__VITE_ENVIRONMENT_RUNNER_IMPORT__` convention!

When using vite@8-beta with Vitest users no longer need to add magical '@preserve' keywords in their coverage ignore hints. Originally this work-around was needed due to esbuild's (intentional) lack of support for comment preserving. Oxc has built-in support for JS coverage tools' ignore hints.

Vitest 4.0.15 comes with a cool experimental feature: Imports Breakdown. Every module shows how long it took to load in UI and in the VSCode extension! Pass down `--experimental.printImportBreakdown` to also see it in your terminal. vitest.dev/guide/ui.htm...

Vitest 4.0.11 adds an experimental `fsModuleCache` flag to cache module transforms between reruns. Learn more: vitest.dev/config/exper... This is an opt-in feature, please let us know how it works for you! And example of a single test file that imports a lot of files (~1500). Almost a 50% boost!

I created a package to expose `import "cloudflare:workers"` through Node custom loader and wrangler's `getPlatformProxy`. Here is a React Router RSC framework mode example with Cloudflare KV github.com/hi-ogawa/vit....

Waku now supports custom base. Here is an example of SSG site deployed to Github Pages hi-ogawa.github.io/waku-example... `@vitejs/plugin-rsc` takes care of base path for handling static assets, so the required change on Waku was only application routing logic github.com/wakujs/waku/...

My talk slides are available here hiroshi-talks.vercel.app/2025-10-25/1 also with source code in github.com/hi-ogawa/talks It was a great experience to talk with many awesome folks in person! Thanks @vuefes.bsky.social for the opportunity!

This is possible in principle though there's some limitations github.com/hi-ogawa/vit.... It turns out React Router RSC API allows overriding internal RSC requests without patching global `fetch`, Not so obvious demo, but here "server" component is accessing `window.navigator`. 😄

First time speaking at a conference!

I wrote a proposal for improving client assets management on Vite SSR application by introducing `?assets` query import. It includes many examples to demonstrate how it can be used in various routers and frameworks setup. Feedback is appreciated! github.com/vitejs/vite/...

I just realized my name is on React 19.2.0 release note. Due to client reference being lazy component, it was super tricky for Vite RSC and Waku (though we ended up finding a workaround). I'm glad I was able to land my first PR on React to fix this!

Quick improvement to reduce potential confusion of "use server" on React Router RSC framework mode github.com/vitejs/vite-... Previously following "use server" is silently ignored, but this should be flagged as build error as React router inject `"use client"` for `export default` routes.

I've been experimenting with Nitro and made a plugin for `@vitejs/plugin-rsc`-based app to be deployed anywhere. Here is an example with React Router RSC! github.com/hi-ogawa/rea...

Improved the error message of invalid `server-only` and `client-only` imports on Vite RSC plugin! These "only" packages provide errors only during runtime on their own, but I didn't see any reason not to surface as build time error, so it has been included as a "plugin feature".

Not as fancy as `next/font`, but simple font optimization (self hosted font + preload link) is super easy thanks to fontsource fontsource.org/docs/getting...

RSC transform utility is available from `@vitejs/plugin-rsc/transforms` since v0.4.29 (just released). github.com/vitejs/vite-... This utility was initially in `@hiogawa/transforms` but moved inside `@vitejs/plugin-rsc` for easier maintenance, and then now it became usable standalone again 😀

Inspired by Parcel, `@vitejs/plugin-rsc` recently changed `"use client"` chunking strategy and it's now optimized based on how they are imported on server. This works nicely with route created by `import.meta.glob` since it merges client components based on page usages. github.com/vitejs/vite-...

RSC support is now included in Vite documentation! vite.dev/plugins/#vit... It's mostly just a link to the plugin readme though. Any feedback on documentation is welcome! 🙂

After I saw Qwik team's Rollup PR for merging merging `this.emitFile` chunks github.com/rollup/rollu..., I was interested to try out the same idea for optimizing `"use client"` chunks and it looks like this works beautifully! github.com/hi-ogawa/vit...

／ 📢 Vue Fes Japan 2025 – First Speakers Announced! 🔥 ＼ We're thrilled to welcome an amazing speaker lineup for Vue Fes Japan 2025! ➡️ Website: vuefes.jp/2025/en/spea... 🔜 More speakers coming soon! 📢 CFP opens Mon, June 2 at 12:00 PM JST 👀 Stay tuned! 🔥 #vuefes #vuejs

Setting up Windows CI for the first time on my own repo github.com/hi-ogawa/vit... Someone reported React router demo is broken on Windows but it's now fixed! I was afraid this might become a nightmare CI debugging session, but it turned out it's just a usual path issue 😄

vite-plugin-inspect works great on RSC app! Here is a screenshot of "use client/server" transform in React Router demo github.com/hi-ogawa/rsc... This is so convenience and I've also added it to `react-server-dom-vite` PR's `fixtures/flight-vite` github.com/facebook/rea...

At this point, I'm just copying all the demos by React router team 😅, but I think this is a cool part of RSC. As long as React router API is aligned with RSC convention and Bundlers support the convention, the same demo should work. Thanks React Router and Parcel for opening up this opportunity!

I ported React Router RSC Movies demo to Vite. github.com/hi-ogawa/rsc... RSC bundler feature is encapsulated in the package `@hiogawa/vite-rsc` and React Router RSC API integration is found in `./react-router-vite`. The latter part is mostly a copy of `parcel-plugin-react-router`.

This is very exciting! React router and Parcel has shown the proper boundary of RSC support between application layer and as bundler layer. Jacob shared their work with me early and that has been guiding me better for RSC support on Vite. Thanks for the shout out in the post!🙏

I just updated `react-server-dom-vite` PR with css import support github.com/facebook/rea.... I'm not sure if this is a right direction, but this seems to nicely handle css code split at each client reference level and it might potentially work as "framework-less" abstraction for Vite RSC.

This was due to Vite module factory function's +2 lines offset, which is handled internally for SSR by adding `;;` , but we need to do the same in `findSourceMapURL`. `registerServerReference` and console replay positions are now right on the spot on devtools! github.com/hi-ogawa/vit...

Testing a nice little RSC feature `findSourceMapURL` on Vite. It looks like this allows jumping to server actions on React dev tools. `createServerReference` is right on the spot, but `registerServerReference` seems off a few lines. I wonder if this is due to `Error.stack` behavior on Vite SSR 🤔

Sneaking in Vitest browser mode on Oxc repo 😄 github.com/oxc-project/... The PR added a test for napi-rs wasi build of oxc parser, which involves wasm, shared memory, and web workers.

I've been curious about how type bundling is done by rollup-plugin-dts github.com/Swatinem/rol.... Just to see a glimpse of the idea, I made a quick playground to dump their internal estree ast github.com/hi-ogawa/rep.... I didn't expect invalid js code coming out 😄

Huge improvement for Vitest development workflow, thanks to isolated declaration! I didn't think the migration was possible until I see PRs by @sxzz.dev. Just started to sponsor Kevin for the amazing work!