Prefetch

Astro ships a built-in prefetch script that warms up navigation by fetching link targets ahead of click. Source: packages/astro/src/prefetch/.

Purpose

Make navigations feel instant on slow networks by issuing a fetch (or <link rel="prefetch">) for likely-next pages. Configurable per-link with the data-astro-prefetch attribute.

Key files

File	Purpose
packages/astro/src/prefetch/index.ts	The browser runtime (link observer + prefetch dispatcher).
packages/astro/src/prefetch/vite-plugin-prefetch.ts	Vite plugin that injects the prefetch script into the page.

Public types for prefetch config live in packages/astro/src/types/public/config.ts.

Configuration

import { defineConfig } from 'astro/config';

export default defineConfig({
  prefetch: {
    prefetchAll: false, // Default: only links with data-astro-prefetch
    defaultStrategy: 'hover', // 'tap' | 'hover' | 'viewport' | 'load'
  },
});

Per-link override:

<a href="/about" data-astro-prefetch="viewport">About</a>
<a href="/big-page" data-astro-prefetch="false">Skip prefetch</a>

Strategies

Strategy	When the prefetch fires
tap	mousedown / touchstart — first frame of intent.
hover	mouseenter after a short delay.
viewport	IntersectionObserver reports the link is visible.
load	Immediately on page load.

The runtime observes links matching either the global setting or data-astro-prefetch="…", computes the URL, and schedules a fetch (with a small in-memory cache to avoid duplicates).

How it works

graph LR
    A[Page load] --> B[Prefetch runtime starts]
    B --> C[Find matching links]
    C --> D{Strategy?}
    D -- viewport --> E[IntersectionObserver]
    D -- hover --> F[mouseenter timer]
    D -- tap --> G[mousedown / touchstart]
    D -- load --> H[Schedule immediately]
    E --> I[fetch(href, { priority: 'low' })]
    F --> I
    G --> I
    H --> I
    I --> J[(in-memory cache)]

Combined with view transitions, prefetch turns most navigations into a sub-100ms experience.

Related pages

• features / view transitions
• systems / Vite plugins