feat(options): make enhancers async ready without breaking changes

packages/@vuepress/core/lib/node/Page.js

@@ -142,7 +142,7 @@ module.exports = class Page {
     this._computed = computed
     this._localePath = computed.$localePath
 
-    this.enhance(enhancers)
+    await this.enhance(enhancers)
     this.buildPermalink()
   }
 
@@ -282,13 +282,13 @@ module.exports = class Page {
    * @api private
    */
 
-  enhance (enhancers) {
+  async enhance (enhancers) {
     for (const { name: pluginName, value: enhancer } of enhancers) {
       try {
-        enhancer(this)
+        await enhancer(this)
       } catch (error) {
         console.log(error)
-        throw new Error(`[${pluginName}] excuete extendPageData failed.`)
+        throw new Error(`[${pluginName}] execute extendPageData failed.`)
       }
     }
   }

packages/@vuepress/core/lib/node/__tests__/prepare/Page.spec.js

@@ -102,5 +102,54 @@ describe('Page', () => {
     expect(page._content.startsWith('---')).toBe(true)
     expect(page._strippedContent.startsWith('---')).toBe(false)
   })
+
+  describe('enhance - ', () => {
+    let page
+    let enhancers
+
+    beforeEach(() => {
+      page = new Page({ path: '/' }, app)
+      enhancers = [
+        {
+          pluginName: 'foo',
+          value: jest.fn()
+        },
+        {
+          pluginName: 'foo',
+          value: jest.fn()
+        }
+      ]
+      global.console.log = jest.fn()
+    })
+
+    test('should loop over sync enhancers', async () => {
+      await page.enhance(enhancers)
+
+      return enhancers.map(enhancer => expect(enhancer.value).toBeCalled())
+    })
+
+    test('should loop over sync and async enhancers', async () => {
+      const mixedEnhancers = [...enhancers, {
+        pluginName: 'blog',
+        value: jest.fn().mockResolvedValue({})
+      }]
+      await page.enhance(mixedEnhancers)
+
+      return mixedEnhancers.map(enhancer => expect(enhancer.value).toBeCalled())
+    })
+
+    test('should log when enhancing when failing', async () => {
+      const error = { errorMessage: 'this is an error message' }
+      expect.assertions(1)
+      try {
+        await page.enhance([{
+          pluginName: 'error-plugin',
+          value: jest.fn().mockRejectedValue(error)
+        }])
+      } catch (e) {
+        expect(console.log).toBeCalledWith(error)
+      }
+    })
+  })
 })
 

packages/docs/docs/plugin/option-api.md

@@ -280,7 +280,7 @@ import { SOURCE_DIR } from '@dynamic/constants'
 
 ## extendPageData
 
-- Type: `Function`
+- Type: `Function|AsyncFunction`
 - Default: `undefined`
 
 A function used to extend or edit the [$page](../guide/global-computed.md#page) object. This function will be invoking once for each page at compile time.
@@ -308,6 +308,16 @@ module.exports = {
 }
 ```
 
+Note that `extendPageData` can also be defined as an asynchronous function.
+
+```js
+module.exports = {
+  async extendPageData ($page) {
+    $page.xxx = await getAsyncData()
+  }
+}
+```
+
 ::: warning Note
 These fields starting with an `_` means you can only access them during build time.
 :::