Astro Page 37

Welcome to Astro!

Astro is a new kind of static site builder that delivers lightning-fast performance with a modern developer experience. Astro borrowed the best parts of our favorite tools and then added a few innovations, including:

🚀 Bring Your Own Framework (BYOF): Build your site using React, Svelte, Vue, Preact, web components, or just plain ol’ HTML + JavaScript.
🚀 100% Static HTML, No JS: Astro renders your entire page to static HTML, removing all JavaScript from your final build by default.
🚀 On-Demand Components: Need some JS? Astro can automatically hydrate interactive components when they become visible on the page. If the user never sees it, they never load it.
🚀 Fully-Featured: Astro supports TypeScript, Scoped CSS, CSS Modules, Sass, Tailwind, Markdown, MDX, and any of your favorite npm packages.
🚀 SEO Enabled: Automatic sitemaps, RSS feeds, pagination and collections take the pain out of SEO and syndication.

How it works

Astro works a lot like a static site generator. If you have ever used Eleventy, Hugo, or Jekyll (or even a server-side web framework like Rails, Laravel, or Django) then you should feel right at home with Astro.

In Astro, you compose your website using UI components from your favorite JavaScript web framework (React, Svelte, Vue, etc). Astro renders your entire site to static HTML during the build. The result is a fully static website with all JavaScript removed from the final page. No monolithic JavaScript application required, just static HTML that loads as fast as possible in the browser regardless of how many UI components you used to generate it.

Of course, sometimes client-side JavaScript is inevitable. Image carousels, shopping carts, and auto-complete search bars are just a few examples of things that require some JavaScript to run in the browser. This is where Astro really shines: When a component needs some JavaScript, Astro only loads that one component (and any dependencies). The rest of your site continues to exist as static, lightweight HTML.

In other full-stack web frameworks this level of per-component optimization would be impossible without loading the entire page in JavaScript, delaying interactivity. In Astro, this kind of partial hydration is built into the tool itself.

You can even automatically defer components to only load once they become visible on the page with the :visible modifier.

This new approach to web architecture is called islands architecture. We didn’t coin the term, but Astro may have perfected the technique. We are confident that an HTML-first, JavaScript-only-as-needed approach is the best solution for the majority of content-based websites.