Astro

Astro is a web framework popularized for "Islands Architecture". It ships zero JavaScript to the client by default, hydrating only the interactive parts. Astro 5 (2025) introduces Server Islands.

When to Use

Content Sites: Blogs, Documentation, Marketing sites.
Multi-Framework: Use React, Vue, and Svelte components on the same page.
Performance: Hard to beat for static content.

Quick Start

---
// Server-side code (Frontmatter) runs at build/request time
const data = await fetch('https://api.myjson.com').then(r => r.json());
---

<html>
  <body>
    <h1>{data.title}</h1>
    <!-- Client Directive: This React component hydrates on load -->
    <MyReactComponent client:load />

    <!-- This Svelte component hydrates only when visible -->
    <MySvelteComponent client:visible />
  </body>
</html>

Core Concepts

Islands Architecture

The page is static HTML. Interactive widgets are "islands" floating in it. They hydrate independently.

Server Islands (Astro 5)

Async islands. The page loads instantly (static), and a specific island (e.g., "User Profile") loads asynchronously from the server and fades in.

Content Collections

Type-safe way to manage Markdown/MDX content.

const blogCollection = defineCollection({
  schema: z.object({ title: z.string(), date: z.date() }),
});

Best Practices (2025)

Do:

Use Server Islands: For dynamic personalization (e.g., "Logged in as Jeevan") without forcing the whole page to be dynamic (SSR).
Use <Image />: Astro's optimized image component is essential for LCP.
Mix Frameworks: Don't be afraid to use React for a complex search bar and Svelte for a simple toggle on the same site.

Don't:

Don't use for complex dashboards: While possible (Hybrid Rendering), Next.js or Remix are often better suited for highly dynamic, authenticated apps.

References

Astro Documentation

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