astro/packages/markdown/remark/src/remark-slug.ts

/**
 * @typedef {import('mdast').Root} Root
 * @typedef {import('hast').Properties} Properties
 */

import {toString} from 'mdast-util-to-string'
import {visit} from 'unist-util-visit'
import BananaSlug from 'github-slugger'

const slugs = new BananaSlug()

/**
 * Plugin to add anchors headings using GitHub’s algorithm.
 *
 * @type {import('unified').Plugin<void[], Root>}
 */
export default function remarkSlug() {
  return (tree: any) => {
    slugs.reset()
    visit(tree, (node) => {
      console.log(node);
    });
    visit(tree, 'heading', (node) => {
      const data = node.data || (node.data = {})
      const props = /** @type {Properties} */ (
        data.hProperties || (data.hProperties = {})
      )
      let id = props.id
      id = id ? slugs.slug(String(id), true) : slugs.slug(toString(node))
      data.id = id;
      props.id = id;
    })
  }
}