fix(client): only update head if needed (#3017)

src/client/app/composables/head.ts

@@ -8,7 +8,7 @@ import {
 import type { Route } from '../router'
 
 export function useUpdateHead(route: Route, siteDataByRouteRef: Ref<SiteData>) {
-  let managedHeadTags: HTMLElement[] = []
+  let managedHeadElements: (HTMLElement | undefined)[] = []
   let isFirstUpdate = true
 
   const updateHeadTags = (newTags: HeadConfig[]) => {
@@ -19,13 +19,25 @@ export function useUpdateHead(route: Route, siteDataByRouteRef: Ref<SiteData>) {
       return
     }
 
-    managedHeadTags.forEach((el) => document.head.removeChild(el))
-    managedHeadTags = []
-    newTags.forEach((headConfig) => {
-      const el = createHeadElement(headConfig)
-      document.head.appendChild(el)
-      managedHeadTags.push(el)
+    const newElements: (HTMLElement | undefined)[] =
+      newTags.map(createHeadElement)
+
+    managedHeadElements.forEach((oldEl, oldIndex) => {
+      const matchedIndex = newElements.findIndex(
+        (newEl) => newEl?.isEqualNode(oldEl ?? null)
+      )
+      if (matchedIndex !== -1) {
+        delete newElements[matchedIndex]
+      } else {
+        oldEl?.remove()
+        delete managedHeadElements[oldIndex]
+      }
     })
+
+    newElements.forEach((el) => el && document.head.appendChild(el))
+    managedHeadElements = [...managedHeadElements, ...newElements].filter(
+      Boolean
+    )
   }
 
   watchEffect(() => {
@@ -35,14 +47,19 @@ export function useUpdateHead(route: Route, siteDataByRouteRef: Ref<SiteData>) {
     const frontmatterHead = (pageData && pageData.frontmatter.head) || []
 
     // update title and description
-    document.title = createTitle(siteData, pageData)
+    const title = createTitle(siteData, pageData)
+    if (title !== document.title) {
+      document.title = title
+    }
 
     const description = pageDescription || siteData.description
     let metaDescriptionElement = document.querySelector(
       `meta[name=description]`
     )
     if (metaDescriptionElement) {
-      metaDescriptionElement.setAttribute('content', description)
+      if (metaDescriptionElement.getAttribute('content') !== description) {
+        metaDescriptionElement.setAttribute('content', description)
+      }
     } else {
       createHeadElement(['meta', { name: 'description', content: description }])
     }