fetchHTML() — astro Function Reference

Architecture documentation for the fetchHTML() function in router.ts from the astro codebase.

Function typescript CoreAstro RenderingEngine called by 1

Entity Profile

CoreAstro→ RenderingEngine→ fetchHTML() — astro Function Reference

Dependency Diagram

graph TD
  5a0af174_e810_2fce_864c_1a4fecf4bc03["fetchHTML()"]
  2b5c33e2_176e_e839_f05f_7f10493f4f74["router.ts"]
  5a0af174_e810_2fce_864c_1a4fecf4bc03 -->|defined in| 2b5c33e2_176e_e839_f05f_7f10493f4f74
  6b23b6bb_d4a4_83cb_3896_2e31c0316793["transition()"]
  6b23b6bb_d4a4_83cb_3896_2e31c0316793 -->|calls| 5a0af174_e810_2fce_864c_1a4fecf4bc03
  style 5a0af174_e810_2fce_864c_1a4fecf4bc03 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

packages/astro/src/transitions/router.ts lines 93–122

async function fetchHTML(
	href: string,
	init?: RequestInit,
): Promise<null | { html: string; redirected?: string; mediaType: DOMParserSupportedType }> {
	try {
		// Apply adapter-specific headers for internal fetches
		const headers = new Headers(init?.headers);
		for (const [key, value] of Object.entries(internalFetchHeaders) as [string, string][]) {
			headers.set(key, value);
		}
		const res = await fetch(href, { ...init, headers });
		const contentType = res.headers.get('content-type') ?? '';
		// drop potential charset (+ other name/value pairs) as parser needs the mediaType
		const mediaType = contentType.split(';', 1)[0].trim();
		// the DOMParser can handle two types of HTML
		if (mediaType !== 'text/html' && mediaType !== 'application/xhtml+xml') {
			// everything else (e.g. audio/mp3) will be handled by the browser but not by us
			return null;
		}
		const html = await res.text();
		return {
			html,
			redirected: res.redirected ? res.url : undefined,
			mediaType,
		};
	} catch {
		// can't fetch, let someone else deal with it.
		return null;
	}
}