Astro

--- name: astro description: "Build content-focused websites with Astro : zero JS by default, islands architecture, multi-framework components, and Markdown/MDX support." category: frontend risk: safe source: community date_added: "2026-03-18" author: suhaibjanjua tags: [astro, ssg, ssr, islands, content, markdown, mdx, performance] tools: [claude, cursor, gemini] --- # Astro Web Framework ## Overview Astro is a web framework designed for content-rich websites : blogs, docs, portfolios, marketing sites, and e-commerce. Its core innovation is the Islands Architecture: by default, Astro ships zero JavaScript to the browser. Interactive components are selectively hydrated as isolated "islands." Astro supports React, Vue, Svelte, Solid, and other UI frameworks simultaneously in the same project, letting you pick the right tool per component. ## When to Use This Skill - Use when building a blog, documentation site, marketing page, or portfolio - Use when performance and Core Web Vitals are the top priority - Use when the project is content-heavy with Markdown or MDX files - Use when you want SSG (static) output with optional SSR for dynamic routes - Use when the user asks about .astro files, Astro.props, content collections, or client: directives ## How It Works ### Step 1: Project Setup ``bash npm create astro@latest my-site cd my-site npm install npm run dev ` Add integrations as needed: `bash npx astro add tailwind # Tailwind CSS npx astro add react # React component support npx astro add mdx # MDX support npx astro add sitemap # Auto sitemap.xml npx astro add vercel # Vercel SSR adapter ` Project structure: ` src/ pages/ ← File-based routing (.astro, .md, .mdx) layouts/ ← Reusable page shells components/ ← UI components (.astro, .tsx, .vue, etc.) content/ ← Type-safe content collections (Markdown/MDX) styles/ ← Global CSS public/ ← Static assets (copied as-is) astro.config.mjs ← Framework config ` ### Step 2: Astro Component Syntax .astro files have a code fence at the top (server-only) and a template below: `astro --- // src/components/Card.astro // This block runs on the server ONLY : never in the browser interface Props { title: string; href: string; description: string; } const { title, href, description } = Astro.props; --- <article class="card"> <h2><a href={href}>{title}</a></h2> <p>{description}</p> </article> <style> /* Scoped to this component automatically */ .card { border: 1px solid #eee; padding: 1rem; } </style> ` ### Step 3: File-Based Pages and Routing ` src/pages/index.astro → / src/pages/about.astro → /about src/pages/blog/[slug].astro → /blog/:slug (dynamic) src/pages/blog/[...path].astro → /blog/* (catch-all) ` Dynamic route with getStaticPaths: `astro --- // src/pages/blog/[slug].astro export async function getStaticPaths() { const posts = await getCollection('blog'); return posts.map(post => ({ params: { slug: post.slug }, props: { post }, })); } const { post } = Astro.props; const { Content } = await post.render(); --- <h1>{post.data.title}</h1> <Content /> ` ### Step 4: Content Collections Content collections give you type-safe access to Markdown and MDX files: `typescript // src/content/config.ts import { z, defineCollection } from 'astro:content'; const blog = defineCollection({ type: 'content', schema: z.object({ title: z.string(), date: z.coerce.date(), tags: z.array(z.string()).default([]), draft: z.boolean().default(false), }), }); export const collections = { blog }; ` `astro --- // src/pages/blog/index.astro import { getCollection } from 'astro:content'; const posts = (await getCollection('blog')) .filter(p => !p.data.draft) .sort((a, b) => b.data.date.valueOf() - a.data.date.valueOf()); --- <ul> {posts.map(post => ( <li> <a href={/blog/${post.slug}}>{post.data.title}</a> <time>{post.data.date.toLocaleDateString()}</time> </li> ))} </ul> ` ### Step 5: Islands : Selective Hydration By default, UI framework components render to static HTML with no JS. Use client: directives to hydrate: `astro --- import Counter from '../components/Counter.tsx'; // React component import VideoPlayer from '../components/VideoPlayer.svelte'; --- <!-- Static HTML : no JavaScript sent to browser --> <Counter initialCount={0} /> <!-- Hydrate immediately on page load --> <Counter initialCount={0} client:load /> <!-- Hydrate when the component scrolls into view --> <VideoPlayer src="/demo.mp4" client:visible /> <!-- Hydrate only when browser is idle --> <Analytics client:idle /> <!-- Hydrate only on a specific media query --> <MobileMenu client:media="(max-width: 768px)" /> ` ### Step 6: Layouts ``astro --- // src/layouts/BaseLayout.astro interface Props { title: string; description?: string; } const { tit