Nuxt 3.12

We're on the road to the release of Nuxt 4, but we've not held back in Nuxt v3.12.

🚀 Testing Nuxt 4 changes

Nuxt 4 is on the horizon, and it's now possible to test out the behaviour changes that will be coming in the next major release (#26925) by setting an option in your nuxt.config file:

export default defineNuxtConfig({
  future: {
    compatibilityVersion: 4,
  },
})

As we've been merging PRs for Nuxt 4, we've been enabling them behind this flag. As much as possible we're aiming for backwards compatibility - our test matrix is running the same fixtures in both v3 and v4 compatibility mode.

There is a lot to say here, with 10+ different PRs and behaviour changes documented and testable, but for full details, including migration steps, see the v4 upgrade documentation.

We'd be very grateful for early testing of what's coming in Nuxt 4! 🙏

📜 Nuxt Scripts auto-install

We've been gradually working to release Nuxt Scripts. It's currently in public preview, but we're near a public release, so we've added some stubs for composables that (when used) will prompt installing the @nuxt/scripts module.

👉 Watch out for the launch - and an article explaining more!

🌈 Layer auto-registration and bugfixes

Just like ~/modules, any layers within your project in the ~/layers directory will now be automatically registered as layers in your project (#27221).

We also now correctly load layer dependencies, which should resolve a range of issues with monorepos and git installations (#27338).

🌐 Built-in accessibility improvements

We now have a built-in <NuxtRouteAnnouncer> component and corresponding useRouteAnnouncer composable, which will be added by default to new Nuxt templates going forward.

For full details, see the original PR (#25741) and documentation.

We're continuing to work on nuxt/a11y - expect to hear more on that in future!

🔥 Performance improvements

We've landed some performance improvements as well, many of which are behind the compatibilityVersion: 4 flag, such as a move away from deeply reactive asyncData payloads.

Significant improvements include deduplicating modules (#27475) - which will apply mostly to layer users who specify modules in their layers. In one project, we saw 30s+ improvement in starting Nuxt.

We've also improved Vite dev server start up time by excluding common ESM dependencies from pre-bundling, and would suggest module authors consider doing the same (#27372).

We improved chunk determinism, so sequential builds should be less likely to have completely different chunk hashes (#27258).

And we tree shake more client-only composables from your server builds (#27044), and have reduced the size of server component payloads (#26863).

👨‍👩‍👧‍👦 Multi-app support

We've landed a couple of changes that take us toward a place of supporting multi-app natively in Nuxt, including a multiApp experimental flag (#27291) and the ability to have multiple Nuxt app instances running in parallel at runtime (#27068).

While it's not yet ready, please do follow along on the tracker issue, and feel free to pitch in if this is interesting to you.

⛑️ DX wins

We now serialise more things in your dev server logs, including VNodes (#27309) and URLs. We also addressed a bug that could lead to a frozen dev server.

When accessing private runtime config in the browser, we now let you know with a more informative error message (#26441).

🪨 Stabilising features

We've removed some experimental options that have been stabilised and which we feel no longer need to be configurable:

• experimental.treeshakeClientOnly (enabled by default since v3.0.0)
• experimental.configSchema (enabled by default since v3.3.0)
• experimental.polyfillVueUseHead (disabled since v3.4.0) - implementable in user-land with plugin
• experimental.respectNoSSRHeader (disabled since v3.4.0) - implementable in user-land with server middleware

We've also enabled scanPageMeta by default (#27134). This pulls out any page metadata in your definePageMeta macro, and makes it available to modules (like @nuxtjs/i18n) so they can augment it.

This unlocks much better module/typed routing integration, but has a potential performance cost - so please file an issue if you experience any problems.

💪 Type improvements

We now have support for typed #fallback slots in server components (#27097).

We've also improved some defaults in your generated tsconfig.json, including setting module: 'preserve' if you have a locally installed TypeScript v5.4 version (see docs) - see #26667, #27485.

📦 Module author/power user improvements

We have shipped a range of type improvements for module authors, including:

• support for typed module options in installModule (#26744)
• the option to specify compatibility with certain builders (vite/webpack) in module options (#27022)
• a new onPrehydrate hook for hooking into the browser hydration cycle (#27037)
• the ability to access and update resolved runtime configuration within modules, with new build-time useRuntimeConfig and updateRuntimeConfig utils (#27117)

🎨 Inlined UI templates

If you previously used @nuxt/ui-templates then it may be worth knowing that we have moved them from a separate repository into the nuxt/nuxt monorepo. (This is purely a refactor rather than a change, although you can expect some new designs for Nuxt v4.)

✅ Upgrading

As usual, our recommendation for upgrading is to run:

npx nuxi@latest upgrade --force

This will refresh your lockfile as well, and ensures that you pull in updates from other dependencies that Nuxt relies on, particularly in the unjs ecosystem.

Full Release Notes

A huge thank you to the 75+ Nuxt contributors and community members who have been part of this release. ❤️

Finally, thank you for reading this far! We hope you enjoy v3.12, and please do let us know if you have any feedback or issues. 🙏

Happy Nuxting ✨