fix(client): resolve SVG links when prefetching (#5442)

__tests__/e2e/prefetch/html.md

@@ -0,0 +1 @@
+# HTML link destination

__tests__/e2e/prefetch/index.md

@@ -0,0 +1,15 @@
+---
+sidebar: false
+outline: false
+---
+
+# Link prefetching
+
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="400" height="150">
+  <a href="./svg.html"><text x="10" y="25">SVG link</text></a>
+  <a href="./svg.html#section"><text x="10" y="50">Same page, another hash</text></a>
+  <a xlink:href="./xlink.html"><text x="10" y="75">SVG xlink</text></a>
+  <a href="./new-tab.html" target="_blank"><text x="10" y="100">New tab</text></a>
+</svg>
+
+[HTML link](./html.md)

__tests__/e2e/prefetch/new-tab.md

@@ -0,0 +1 @@
+# New tab destination

__tests__/e2e/prefetch/prefetch.test.ts

@@ -0,0 +1,43 @@
+test.runIf(process.env.VITE_TEST_BUILD)(
+  'prefetches SVG links without errors and respects new-tab targets',
+  async () => {
+    const errors: string[] = []
+    const onPageError = (error: Error) => errors.push(error.message)
+    page.on('pageerror', onPageError)
+
+    try {
+      await goto('/prefetch/')
+
+      await expect
+        .poll(
+          async () => ({
+            errors,
+            pages: await page
+              .locator('link[rel="prefetch"]')
+              .evaluateAll((links) =>
+                links
+                  .map(
+                    (link) =>
+                      link
+                        .getAttribute('href')
+                        ?.match(/prefetch_(.*?)\.md\./)?.[1]
+                  )
+                  .filter(Boolean)
+                  .sort()
+              )
+          }),
+          { timeout: 10_000 }
+        )
+        .toEqual({ errors: [], pages: ['html', 'svg', 'xlink'] })
+
+      await page.locator('svg a[href="./svg.html"]').click()
+      await page.waitForSelector('h1', { state: 'visible' })
+      await expect
+        .poll(() => page.locator('h1').textContent())
+        .toContain('SVG link destination')
+      expect(errors).toEqual([])
+    } finally {
+      page.off('pageerror', onPageError)
+    }
+  }
+)

__tests__/e2e/prefetch/svg.md

@@ -0,0 +1,3 @@
+# SVG link destination
+
+## Section

__tests__/e2e/prefetch/xlink.md

@@ -0,0 +1 @@
+# SVG xlink destination

src/client/app/composables/preFetch.ts

@@ -10,6 +10,12 @@ import { inBrowser, pathToFile } from '../utils'
 const hasFetched = new Set<string>()
 const createLink = () => document.createElement('link')
 
+const getLinkUrl = (link: HTMLAnchorElement | SVGAElement) =>
+  new URL(
+    link.href instanceof SVGAnimatedString ? link.href.animVal : link.href,
+    link.baseURI
+  )
+
 const viaDOM = (url: string) => {
   const link = createLink()
   link.rel = `prefetch`
@@ -64,9 +70,9 @@ export function usePrefetch() {
     observer = new IntersectionObserver((entries) => {
       entries.forEach((entry) => {
         if (entry.isIntersecting) {
-          const link = entry.target as HTMLAnchorElement
+          const link = entry.target as HTMLAnchorElement | SVGAElement
           observer!.unobserve(link)
-          const { pathname } = link
+          const { pathname } = getLinkUrl(link)
           if (!hasFetched.has(pathname)) {
             hasFetched.add(pathname)
             const pageChunkPath = pathToFile(pathname)
@@ -80,12 +86,7 @@ export function usePrefetch() {
       document
         .querySelectorAll<HTMLAnchorElement | SVGAElement>('#app a')
         .forEach((link) => {
-          const { hostname, pathname } = new URL(
-            link.href instanceof SVGAnimatedString
-              ? link.href.animVal
-              : link.href,
-            link.baseURI
-          )
+          const { hostname, pathname } = getLinkUrl(link)
           const extMatch = pathname.match(/\.\w+$/)
           if (extMatch && extMatch[0] !== '.html') {
             return
@@ -94,7 +95,7 @@ export function usePrefetch() {
           if (
             // only prefetch same tab navigation, since a new tab will load
             // the lean js chunk instead.
-            link.target !== '_blank' &&
+            link.getAttribute('target') !== '_blank' &&
             // only prefetch inbound links
             hostname === location.hostname
           ) {