fix(markdown): preserve queries on index page links (#5436)

__tests__/unit/node/markdown/plugins/link.test.ts

@@ -61,6 +61,42 @@ describe('node/markdown/plugins/link', () => {
     expect(env.links).toEqual(['./missing'])
     expect(env.linkLines).toEqual([3])
   })
+
+  test.each([false, true])(
+    'preserves index page queries (cleanUrls: %s)',
+    async (cleanUrls) => {
+      for (const [source, expected] of [
+        ['/guide/index.md?lang=fr', '/guide/?lang=fr'],
+        [
+          './index.md?lang=fr&mode=full#Hello%20World',
+          './?lang=fr&mode=full#hello-world'
+        ],
+        [
+          '/guide/index.md?next=/other/index.md#Hello%20World',
+          '/guide/?next=/other/index.md#hello-world'
+        ],
+        [
+          '/guide/index.md?lang=fr#:~:text=Hello%20World',
+          '/guide/?lang=fr#:~:text=Hello%20World'
+        ]
+      ]) {
+        expect(
+          await md.renderAsync(`[link](${source})`, { cleanUrls })
+        ).toContain(`href="${expected}"`)
+      }
+    }
+  )
+
+  test.each([false, true])(
+    'only removes the exact index.md filename (cleanUrls: %s)',
+    async (cleanUrls) => {
+      for (const file of ['indexAmd', 'index.md-extra']) {
+        expect(
+          await md.renderAsync(`[link](/guide/${file})`, { cleanUrls })
+        ).toContain(`href="/guide/${file}${cleanUrls ? '' : '.html'}"`)
+      }
+    }
+  )
 })
 
 describe('node/markdown/plugins/link with a relative base', () => {
@@ -114,6 +150,19 @@ describe('node/markdown/plugins/link with a relative base', () => {
     )
   })
 
+  test.each([false, true])(
+    'preserves index page queries with a relative base (cleanUrls: %s)',
+    async (cleanUrls) => {
+      expect(
+        await render('[link](/guide/index.md?lang=fr#Hello%20World)', {
+          cleanUrls
+        })
+      ).toContain(
+        `href="../guide/${cleanUrls ? '' : 'index.html'}?lang=fr#hello-world"`
+      )
+    }
+  )
+
   test('content-loader renders keep absolute links site-absolute', async () => {
     // content loaders set relativePath but not relativizeUrls — their html
     // is embedded in other pages, so the source's depth must not apply

src/node/markdown/plugins/link.ts

@@ -16,7 +16,7 @@ import {
   type MarkdownEnv
 } from '../../shared'
 
-const indexRE = /(^|.*\/)index.md(#?.*)$/i
+const indexRE = /(^|.*\/)index\.md$/i
 
 export const linkPlugin = (
   md: MarkdownItAsync,
@@ -112,12 +112,11 @@ export const linkPlugin = (
     // directory urls need a server to resolve them, and file:// has none
     const explicitIndex = isRelativeBase(base) && !env.cleanUrls
 
-    const indexMatch = url.match(indexRE)
+    let cleanUrl = url.replace(/[?#].*$/, '')
+    const indexMatch = cleanUrl.match(indexRE)
     if (indexMatch) {
-      const [, path, hash] = indexMatch
+      cleanUrl = indexMatch[1] + (explicitIndex ? 'index.html' : '')
-      url = path + (explicitIndex ? 'index.html' : '') + normalizeHash(hash)
     } else {
-      let cleanUrl = url.replace(/[?#].*$/, '')
       // transform foo.md -> foo[.html]
       if (cleanUrl.endsWith('.md')) {
         cleanUrl = cleanUrl.replace(/\.md$/, env.cleanUrls ? '' : '.html')
@@ -133,9 +132,9 @@ export const linkPlugin = (
       if (explicitIndex && cleanUrl.endsWith('/')) {
         cleanUrl += 'index.html'
       }
-      const parsed = new URL(url, 'http://a.com')
-      url = cleanUrl + parsed.search + normalizeHash(parsed.hash)
     }
+    const parsed = new URL(url, 'http://a.com')
+    url = cleanUrl + parsed.search + normalizeHash(parsed.hash)
 
     // ensure leading . for relative paths
     if (!url.startsWith('/') && !url.startsWith('./')) {