index.ts — astro Source File

Source Code

/*
  NOTE: Be careful about adding dependencies or imports in this file so that it can load quickly in dev.
*/

import { internalFetchHeaders } from 'virtual:astro:adapter-config/client';

const debug = import.meta.env.DEV ? console.debug : undefined;
const inBrowser = import.meta.env.SSR === false;
// Track prefetched URLs so we don't prefetch twice
const prefetchedUrls = new Set<string>();
// Track listened anchors so we don't attach duplicated listeners
const listenedAnchors = new WeakSet<HTMLAnchorElement>();

// User-defined config for prefetch. The values are injected by vite-plugin-prefetch
// and can be undefined if not configured. But it will be set a fallback value in `init()`.
// @ts-expect-error injected global
let prefetchAll: boolean = __PREFETCH_PREFETCH_ALL__;
// @ts-expect-error injected global
let defaultStrategy: string = __PREFETCH_DEFAULT_STRATEGY__;
// @ts-expect-error injected global
let clientPrerender: boolean = __EXPERIMENTAL_CLIENT_PRERENDER__;

interface InitOptions {
	defaultStrategy?: string;
	prefetchAll?: boolean;
}

let inited = false;
/**
 * Initialize the prefetch script, only works once.
 *
 * @param defaultOpts Default options for prefetching if not already set by the user config.
 */
export function init(defaultOpts?: InitOptions) {
	if (!inBrowser) return;

	// Init only once
	if (inited) return;
	inited = true;

	debug?.(`[astro] Initializing prefetch script`);

	// Fallback default values if not set by user config
	prefetchAll ??= defaultOpts?.prefetchAll ?? false;
	defaultStrategy ??= defaultOpts?.defaultStrategy ?? 'hover';

	// In the future, perhaps we can enable treeshaking specific unused strategies
	initTapStrategy();
	initHoverStrategy();
	initViewportStrategy();
	initLoadStrategy();
}

/**
 * Prefetch links with higher priority when the user taps on them
 */
function initTapStrategy() {
	for (const event of ['touchstart', 'mousedown']) {
		document.addEventListener(
			event,
// ... (296 more lines)