feat: expose preprocessHead

Author: antfu

src/markdown.ts

@@ -4,6 +4,7 @@ import { componentPlugin } from '@mdit-vue/plugin-component'
 import { frontmatterPlugin } from '@mdit-vue/plugin-frontmatter'
 import type { TransformResult } from 'vite'
 import type { MarkdownEnv, ResolvedOptions } from './types'
+import { preprocessHead } from './head'
 
 const scriptSetupRE = /<\s*script([^>]*)\bsetup\b([^>]*)>([\s\S]*)<\/script>/mg
 const defineExposeRE = /defineExpose\s*\(/mg
@@ -117,7 +118,7 @@ export function createMarkdown(options: ResolvedOptions) {
         data.excerpt = excerpt
       }
 
-      const { head, frontmatter } = frontmatterPreprocess(data || {}, options)
+      const { head, frontmatter } = frontmatterPreprocess(data || {}, options, preprocessHead)
 
       if (options.excerpt && !excerptKeyOverlapping && frontmatter.excerpt !== undefined)
         delete frontmatter.excerpt

src/options.ts

@@ -1,10 +1,9 @@
 import { toArray } from '@antfu/utils'
-import { preprocessHead } from './head'
-import type { Frontmatter, Options, ResolvedOptions } from './types'
+import type { Options, ResolvedOptions } from './types'
 import { getVueVersion } from './utils'
 
 export function resolveOptions(userOptions: Options): ResolvedOptions {
-  const defaultOptions: Omit<ResolvedOptions, 'frontmatterPreprocess'> = {
+  const defaultOptions: ResolvedOptions = {
     headEnabled: false,
     headField: '',
     frontmatter: true,
@@ -24,17 +23,18 @@ export function resolveOptions(userOptions: Options): ResolvedOptions {
     wrapperClasses: 'markdown-body',
     include: null,
     exclude: null,
-  }
-  const options = userOptions.frontmatterPreprocess
-    ? { ...defaultOptions, ...userOptions }
-    : {
-        ...defaultOptions,
-        ...userOptions,
-        frontmatterPreprocess: (frontmatter: Frontmatter, options: ResolvedOptions) => {
-          const head = preprocessHead(frontmatter, options)
-          return { head, frontmatter }
-        },
+    frontmatterPreprocess: (frontmatter, options, defaults) => {
+      return {
+        head: defaults(frontmatter, options),
+        frontmatter,
       }
+    },
+  }
+
+  const options = {
+    ...defaultOptions,
+    ...userOptions,
+  }
 
   options.wrapperClasses = toArray(options.wrapperClasses)
     .filter((i?: string) => i)

src/types.ts

@@ -3,6 +3,7 @@ import type { ComponentPluginOptions } from '@mdit-vue/plugin-component'
 import type { FrontmatterPluginOptions } from '@mdit-vue/plugin-frontmatter'
 import type { MarkdownItEnv } from '@mdit-vue/types'
 import type { FilterPattern } from '@rollup/pluginutils'
+import type { preprocessHead } from './head'
 
 /** a `<meta />` property in HTML is defined with the following name/values */
 export interface MetaProperty {
@@ -106,7 +107,8 @@ export interface Options {
    */
   frontmatterPreprocess?: (
     frontmatter: Frontmatter,
-    options: ResolvedOptions
+    options: ResolvedOptions,
+    defaultHeadProcess: typeof preprocessHead,
   ) => {
     head: Record<string, any>
     frontmatter: Frontmatter