@mdx-js/language-service/lib/plugins/rehype-mdx-title.js

MDX support for Volar

/**
 * @import {VirtualCodePlugin} from './plugin.js'
 */

/**
 * @param {unknown} options
 * @returns {VirtualCodePlugin}
 */
export function rehypeMdxTitle(options) {
  const opts = typeof options === 'object' && options !== null ? options : {}
  const maxRank = 'maxRank' in opts ? Number(opts.maxRank) : 1
  const name = 'name' in opts ? String(opts.name) : 'title'

  return () => {
    let hasTitle = false

    return {
      visit(node) {
        hasTitle ||= node.type === 'heading' && node.depth <= maxRank
      },

      finalize() {
        return (
          '/** Generated by [rehype-mdx-title](https://github.com/remcohaszing/rehype-mdx-title) */\nexport const ' +
          name +
          ' = /** @type {string' +
          (hasTitle ? '' : ' | undefined') +
          "} */ ('')"
        )
      }
    }
  }
}