astro/dist/prefetch/speculation-rules.js

Astro is a modern site builder with web best practices, performance, and DX front-of-mind.

/**
* Generates static speculation rules JSON using `"source": "document"` with CSS selector matching.
* This produces a deterministic payload that can be hashed at build time for CSP compatibility,
* unlike the dynamic per-URL `"source": "list"` approach in `appendSpeculationRules()`.
*/
export function generateSpeculationRulesContent(prefetchAll) {
	const selector = prefetchAll ? "a" : "a[data-astro-prefetch]";
	return JSON.stringify({
		prerender: [{
			source: "document",
			where: { selector_matches: selector },
			eagerness: "moderate"
		}],
		prefetch: [{
			source: "document",
			where: { selector_matches: selector },
			eagerness: "moderate"
		}]
	});
}