Use unist-util-mdx-define

Since this has options to handle naming conflicts, we now also support
these options.

Author: remcohaszing

package-lock.json

@@ -35,10 +35,10 @@
   },
   "dependencies": {
     "@types/mdast": "^4.0.0",
-    "estree-util-is-identifier-name": "^3.0.0",
     "estree-util-value-to-estree": "^3.0.0",
     "toml": "^3.0.0",
     "unified": "^11.0.0",
+    "unist-util-mdx-define": "^1.0.0",
     "yaml": "^2.0.0"
   },
   "devDependencies": {

package.json

@@ -1,7 +1,6 @@
-import assert from 'node:assert/strict'
 import { test } from 'node:test'
 
-import { compile, compileSync } from '@mdx-js/mdx'
+import { compile } from '@mdx-js/mdx'
 import remarkFrontmatter from 'remark-frontmatter'
 import remarkMdxFrontmatter from 'remark-mdx-frontmatter'
 import { assertEqual, testFixturesDirectory } from 'snapshot-fixtures'
@@ -49,14 +48,3 @@ export default function MDXContent(props = {}) {
 `
   )
 })
-
-test('invalid name', () => {
-  assert.throws(
-    () =>
-      compileSync('---\n\n---\n', {
-        remarkPlugins: [remarkFrontmatter, [remarkMdxFrontmatter, { name: 'Not valid' }]],
-        jsx: true
-      }),
-    /Name should be a valid identifier, got: "Not valid"/
-  )
-})

src/remark-mdx-frontmatter.test.ts

@@ -1,13 +1,13 @@
-import { name as isIdentifierName } from 'estree-util-is-identifier-name'
 import { valueToEstree } from 'estree-util-value-to-estree'
 import { type Literal, type Root } from 'mdast'
 import { parse as parseToml } from 'toml'
 import { type Plugin } from 'unified'
+import { define } from 'unist-util-mdx-define'
 import { parse as parseYaml } from 'yaml'
 
 type FrontmatterParsers = Record<string, (value: string) => unknown>
 
-export interface RemarkMdxFrontmatterOptions {
+export interface RemarkMdxFrontmatterOptions extends define.Options {
   /**
    * If specified, the YAML data is exported using this name. Otherwise, each
    * object key will be used as an export name.
@@ -34,19 +34,16 @@ export interface RemarkMdxFrontmatterOptions {
  */
 const remarkMdxFrontmatter: Plugin<[RemarkMdxFrontmatterOptions?], Root> = ({
   name = 'frontmatter',
-  parsers
+  parsers,
+  ...options
 } = {}) => {
-  if (!isIdentifierName(name)) {
-    throw new Error(`Name should be a valid identifier, got: ${JSON.stringify(name)}`)
-  }
-
   const allParsers: FrontmatterParsers = {
     yaml: parseYaml,
     toml: parseToml,
     ...parsers
   }
 
-  return (ast) => {
+  return (ast, file) => {
     let data: unknown
     const node = ast.children.find((child) => Object.hasOwn(allParsers, child.type))
 
@@ -57,33 +54,7 @@ const remarkMdxFrontmatter: Plugin<[RemarkMdxFrontmatterOptions?], Root> = ({
       data = parser(value)
     }
 
-    ast.children.unshift({
-      type: 'mdxjsEsm',
-      value: '',
-      data: {
-        estree: {
-          type: 'Program',
-          sourceType: 'module',
-          body: [
-            {
-              type: 'ExportNamedDeclaration',
-              specifiers: [],
-              declaration: {
-                type: 'VariableDeclaration',
-                kind: 'const',
-                declarations: [
-                  {
-                    type: 'VariableDeclarator',
-                    id: { type: 'Identifier', name },
-                    init: valueToEstree(data, { preserveReferences: true })
-                  }
-                ]
-              }
-            }
-          ]
-        }
-      }
-    })
+    define(ast, file, { [name]: valueToEstree(data, { preserveReferences: true }) }, options)
   }
 }