appendSpeculationRules() — astro Function Reference

Architecture documentation for the appendSpeculationRules() function in index.ts from the astro codebase.

Function typescript CoreAstro RenderingEngine called by 1

Entity Profile

CoreAstro→ RenderingEngine→ appendSpeculationRules() — astro Function Reference

Dependency Diagram

graph TD
  48f302df_372c_1a3e_b7a1_ac529c030249["appendSpeculationRules()"]
  315e53ea_6d34_137c_ce5c_8c89aca90db9["index.ts"]
  48f302df_372c_1a3e_b7a1_ac529c030249 -->|defined in| 315e53ea_6d34_137c_ce5c_8c89aca90db9
  1502f987_7806_fcef_2f8e_55d799080686["prefetch()"]
  1502f987_7806_fcef_2f8e_55d799080686 -->|calls| 48f302df_372c_1a3e_b7a1_ac529c030249
  style 48f302df_372c_1a3e_b7a1_ac529c030249 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

packages/astro/src/prefetch/index.ts lines 332–355

function appendSpeculationRules(url: string, eagerness: PrefetchOptions['eagerness']) {
	const script = document.createElement('script');
	script.type = 'speculationrules';
	script.textContent = JSON.stringify({
		prerender: [
			{
				source: 'list',
				urls: [url],
				eagerness: eagerness,
			},
		],
		// Currently, adding `prefetch` is required to fallback if `prerender` fails.
		// Possibly will be automatic in the future, in which case it can be removed.
		// https://github.com/WICG/nav-speculation/issues/162#issuecomment-1977818473
		prefetch: [
			{
				source: 'list',
				urls: [url],
				eagerness: eagerness,
			},
		],
	});
	document.head.append(script);
}