fix: insert page title literally into titleTemplate (#5470)

__tests__/unit/shared/shared.test.ts

@@ -1,10 +1,13 @@
 import {
+  createTitle,
   isRelativeBase,
   joinPath,
   mergeHead,
   pageChunkPath,
   relativePathToRoot,
-  type HeadConfig
+  type HeadConfig,
+  type PageData,
+  type SiteData
 } from 'shared/shared'
 
 describe('shared/shared', () => {
@@ -25,6 +28,16 @@ describe('shared/shared', () => {
     })
   })
 
+  describe('createTitle', () => {
+    test('inserts titles containing $ literally into :title templates', () => {
+      const site = { title: 'Site', titleTemplate: ':title - Docs' }
+      const page = { title: 'Using $& and $$ in Bash' }
+      expect(createTitle(site as SiteData, page as PageData)).toBe(
+        'Using $& and $$ in Bash - Docs'
+      )
+    })
+  })
+
   describe('mergeHead', () => {
     test('replaces meta tags with the same key in place', () => {
       expect(

src/shared/shared.ts

@@ -213,7 +213,7 @@ export function createTitle(siteData: SiteData, pageData: PageData): string {
   const template = pageData.titleTemplate ?? siteData.titleTemplate
 
   if (typeof template === 'string' && template.includes(':title')) {
-    return template.replace(/:title/g, title)
+    return template.replace(/:title/g, () => title)
   }
 
   const templateString = createTitleTemplate(siteData.title, template)