nuxt-cos

[!WARNING] Experimental. The Cross-Origin Storage API is an early-stage proposal with no native browser support yet, and the underlying chunk format is not stable. Do not depend on it in production.

A Nuxt module that loads shared dependencies (such as vue) from Cross-Origin Storage (COS). It extracts those dependencies into content-addressed chunks so that a COS-capable browser can reuse the same chunk across different sites instead of downloading it once per origin.

It is a thin Nuxt wrapper around vite-plugin-cross-origin-storage; see that package for how the content addressing and sharing work.

Setup

npx nuxt module add nuxt-cos

Or add it manually:

// nuxt.config.ts
export default defineNuxtConfig({
  modules: ['nuxt-cos'],
})

By default it manages vue and @vue/*. The module only runs in production builds (it is a no-op in dev), and it injects the COS loader into the server-rendered HTML, replacing Nuxt's default entry script.

Configuration

export default defineNuxtConfig({
  modules: ['nuxt-cos'],
  cos: {
    // Packages to extract into COS chunks. Matched against the imported
    // specifier; a plain string is an exact match. Transitive dependencies
    // are collected automatically.
    packages: [/^(?:vue$|@vue\/)/],
  },
})

| Option | Type | Default | Description | | --- | --- | --- | --- | | packages | Array<string \| RegExp> | [/^(?:vue$\|@vue\/)/] | Packages to extract into COS chunks. |

Trying it out

The module is a no-op in dev, so test a production build:

nuxt build && nuxt preview

What to look for:

• In .output/public/_nuxt/, the managed packages are emitted as content-hashed chunks (64-character hex filenames like a1b2c3...e4f5.js).
• View source on the rendered page: Nuxt's default entry <script type="module"> is gone, replaced by a <script id="cos-loader"> containing the loader and an inlined manifest.
• The page still hydrates and is interactive.

Without a COS-capable browser the loader fetches each chunk over the network (the fallback path), so this confirms the chunking and loader work, but not sharing.

To see real Cross-Origin Storage, install the extension, open the preview URL once (the chunks are fetched and stored), then reload or open another site shipping the same Vue version: in DevTools -> Network the hashed chunks are served from the shared store instead of refetched.

For local testing it's safest to load the extension unpacked from web-ai-community/cross-origin-storage-extension.

Browser support

The Cross-Origin Storage API is not yet in any browser. You can try it with the Cross-Origin Storage browser extension. Without it, chunks load over the network as usual, so your site keeps working; it just doesn't share them.

License

MIT