feat(build): provide `siteConfig` in `transformPageData` context (#2163)

docs/reference/site-config.md

@@ -552,21 +552,31 @@ export default {
 
 ### transformPageData
 
-- Type: `(pageData: PageData) => Awaitable<Partial<PageData> | { [key: string]: any } | void>`
+- Type: `(pageData: PageData, ctx: TransformPageContext) => Awaitable<Partial<PageData> | { [key: string]: any } | void>`
 
 `transformPageData` is a hook to transform the `pageData` of each page. You can directly mutate `pageData` or return changed values which will be merged into PageData.
 
+::: warning
+Don't mutate anything inside the `ctx`. 
+:::
+
 ```ts
 export default {
-  async transformPageData(pageData) {
+  async transformPageData(pageData, { siteConfig }) {
     pageData.contributors = await getPageContributors(pageData.relativePath)
   }
 
   // or return data to be merged
-  async transformPageData(pageData) {
+  async transformPageData(pageData, { siteConfig }) {
     return {
       contributors: await getPageContributors(pageData.relativePath)
     }
   }
 }
 ```
+
+```ts
+interface TransformPageContext {
+  siteConfig: SiteConfig
+}
+```

src/node/config.ts

@@ -145,10 +145,15 @@ export interface UserConfig<ThemeConfig = any>
    * PageData transform hook: runs when rendering markdown to vue
    */
   transformPageData?: (
-    pageData: PageData
+    pageData: PageData,
+    ctx: TransformPageContext
   ) => Awaitable<Partial<PageData> | { [key: string]: any } | void>
 }
 
+export interface TransformPageContext {
+  siteConfig: SiteConfig
+}
+
 export interface TransformContext {
   page: string
   siteConfig: SiteConfig

src/node/markdownToVue.ts

@@ -191,7 +191,9 @@ export async function createMarkdownToVueRenderFn(
     }
 
     if (siteConfig?.transformPageData) {
-      const dataToMerge = await siteConfig.transformPageData(pageData)
+      const dataToMerge = await siteConfig.transformPageData(pageData, {
+        siteConfig
+      })
       if (dataToMerge) {
         pageData = {
           ...pageData,