feat!: add more global and computed properties (#152)

BREAKING CHANGE: `$theme` global computed is renamed to `$themeConfig`
to align better with VuePress.

Co-authored-by: Kia King Ishii <kia.king.08@gmail.com>

docs/.vitepress/config.js

@@ -44,6 +44,7 @@ function getGuideSidebar() {
       text: 'Advanced',
       children: [
         { text: 'Frontmatter', link: '/guide/frontmatter' },
+        { text: 'Global Computed', link: '/guide/global-computed' },
         { text: 'Customization', link: '/guide/customization' }
       ]
     }

docs/guide/frontmatter.md

@@ -9,7 +9,7 @@ editLink: true
 ---
 ```
 
-Between the triple-dashed lines, you can set [predefined variables](#predefined-variables), or even create custom ones of your own. These variables can be used via the <code>\$page.frontmatter</code> variable.
+Between the triple-dashed lines, you can set [predefined variables](#predefined-variables), or even create custom ones of your own. These variables can be used via the <code>$frontmatter</code> variable.
 
 Here’s an example of how you could use it in your Markdown file:
 
@@ -19,7 +19,7 @@ title: Docs with VitePress
 editLink: true
 ---
 
-# {{ $page.frontmatter.title }}
+# {{ $frontmatter.title }}
 
 Guide content
 ```

docs/guide/global-computed.md

@@ -0,0 +1,73 @@
+# Global Computed
+
+In VitePress, some core [computed properties](https://v3.vuejs.org/guide/computed.html#computed-properties) can be used by the default theme or custom themes. Or directly in Markdown pages using vue, for example using `$frontmatter.title` to access the title defined in the frontmatter section of the page.
+
+## $site
+
+This is the `$site` value of the site you're currently reading:
+
+```js
+{
+  base: '/',
+  lang: 'en-US',
+  title: 'VitePress',
+  description: 'Vite & Vue powered static site generator.',
+  head: [],
+  locales: {},
+  themeConfig: $themeConfig
+}
+```
+
+## $themeConfig
+
+Refers to `$site.themeConfig`.
+
+```js
+{
+  locales: {},
+  repo: 'vuejs/vitepress',
+  docsDir: 'docs',
+  editLinks: true,
+  editLinkText: 'Edit this page on GitHub',
+  lastUpdated: 'Last Updated',
+  nav: [...],
+  sidebar: { ... }
+}
+```
+
+## $page
+
+This is the `$page` value of the page you're currently reading:
+
+```js
+{
+  relativePath: 'guide/global-computed.md',
+  title: 'Global Computed',
+  headers: [
+    { level: 2, title: '$site', slug: 'site' },
+    { level: 2, title: '$page', slug: '$page' },
+    ...
+  ],
+  frontmatter: $frontmatter,
+  lastUpdated: 1606297645000
+}
+```
+
+## $frontmatter
+
+Reference of `$page.frontmatter`.
+
+```js
+{
+  title: 'Docs with VitePress',
+  editLink: true
+}
+```
+
+## $title
+
+Value of the `<title>` label used for the current page.
+
+## $description
+
+The content value of the `<meta name= "description" content= "...">` for the current page.

src/client/app/index.ts

@@ -82,14 +82,31 @@ export function createApp() {
         return siteDataByRouteRef.value
       }
     },
+    $themeConfig: {
+      get() {
+        return siteDataByRouteRef.value.themeConfig
+      }
+    },
     $page: {
       get() {
         return router.route.data
       }
     },
-    $theme: {
+    $frontmatter: {
       get() {
-        return siteDataByRouteRef.value.themeConfig
+        return router.route.data.frontmatter
+      }
+    },
+    $title: {
+      get() {
+        return router.route.data.title || siteDataByRouteRef.value.title
+      }
+    },
+    $description: {
+      get() {
+        return (
+          router.route.data.description || siteDataByRouteRef.value.description
+        )
       }
     }
   })

src/client/theme-default/components/NavBarTitle.vue

@@ -5,24 +5,17 @@
     :aria-label="`${$site.title}, back to home`"
   >
     <img
-      v-if="$theme.logo"
+      v-if="$themeConfig.logo"
       class="logo"
-      :src="withBase($theme.logo)"
+      :src="withBase($themeConfig.logo)"
       alt="Logo"
     />
     {{ $site.title }}
   </a>
 </template>
 
-<script lang="ts">
-import { defineComponent } from 'vue'
+<script setup lang="ts">
 import { withBase } from '../utils'
-
-export default defineComponent({
-  setup() {
-    return { withBase }
-  }
-})
 </script>
 
 <style scoped>

src/node/markdownToVue.ts

@@ -3,7 +3,7 @@ import matter from 'gray-matter'
 import LRUCache from 'lru-cache'
 import { createMarkdownRenderer, MarkdownOptions } from './markdown/markdown'
 import { deeplyParseHeader } from './utils/parseHeader'
-import { PageData } from '../../types/shared'
+import { PageData, HeadConfig } from '../../types/shared'
 
 const debug = require('debug')('vitepress:md')
 const cache = new LRUCache<string, MarkdownCompileResult>({ max: 1024 })
@@ -41,6 +41,7 @@ export function createMarkdownToVueRenderFn(
     // inject page data
     const pageData: PageData = {
       title: inferTitle(frontmatter, content),
+      description: inferDescription(frontmatter),
       frontmatter,
       headers: data.headers,
       relativePath: file.replace(/\\/g, '/'),
@@ -106,3 +107,26 @@ const inferTitle = (frontmatter: any, content: string) => {
   }
   return ''
 }
+
+const inferDescription = (frontmatter: Record<string, any>) => {
+  if (!frontmatter.head) {
+    return ''
+  }
+
+  return getHeadMetaContent(frontmatter.head, 'description') || ''
+}
+
+const getHeadMetaContent = (
+  head: HeadConfig[],
+  name: string
+): string | undefined => {
+  if (!head || !head.length) {
+    return undefined
+  }
+
+  const meta = head.find(([tag, attrs = {}]) => {
+    return tag === 'meta' && attrs.name === name && attrs.content
+  })
+
+  return meta && meta[1].content
+}

types/shared.d.ts

@@ -24,10 +24,11 @@ export type HeadConfig =
   | [string, Record<string, string>, string]
 
 export interface PageData {
+  relativePath: string
   title: string
-  frontmatter: Record<string, any>
+  description: string
   headers: Header[]
-  relativePath: string
+  frontmatter: Record<string, any>
   lastUpdated: number
 }