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Domain Expansion

Caveats

Diminishing Returns

Let’s get this out of the way first: Domain Expansion is not a silver bullet. This won’t speed up every build process to below 10ms. In fact, in certain cases, it might even slow down your build times due to the caching overhead. Here’s the general rule of thumb:

  1. If you have a fast CPU, you won’t see significant improvements. We can only speed up the build process so much.
  2. On small sites you won’t see any improvements, and might even see a slowdown.

This extension is great for big projects and slow CPUs, but it’s not a one-size-fits-all solution.

Engines

Domain Expansion is very particular about the build environment, and requires you to use Node.js. This is because the integration relies on functions that are only available in V8, the runtime that Node.js uses.

If you use any runtime besides Node.js for building, Domain Expansion will not work. However, you are not required to deploy to Node.js! After the build process is complete, any Astro-compatible runtime can be used to serve the site.

Global State

If you have components with global state, they might behave in weird ways, as Domain Expansion is unable to cache any shared state between components, because every component is built in isolation. This means that when retrieving a component from the cache, none if its side effects will be able to be recreated.

Stale Content

Domain Expansion does not invalidate external content, recompute usage of random values, or datetime usage. The first time a component is rendered, it’s output is cached until the cache is invalidated. For example, calling Date.now() in a component used in multiple locations will cause all locations to return the result of the first render of that component.

Astro Versions

Domain Expansion relies on how two very specific functions are exported from Astro. Specifically where and how $$createComponent and getImage are declared and exported from. If these functions are moved or changed in any way, Domain Expansion will break. Since those functions are part of Astro’s internal API, they can change at any time, even on patch releases.

If you find yourself having any issues with Domain Expansion, please open an issue on the GitHub repository.