Add ability to change section attributes based on heading about remark-sectionize HOT 9 OPEN

// This rehype plugin traverses <section> elements in the document, and if that section's first
// child is a heading (h1, h2, etc), it moves that child's `id` attribute to the section element.

const visit = require('unist-util-visit-parents')

const MAX_HEADING_DEPTH = 6
const HEADINGS = ["h1", "h2", "h3", "h4", "h5", "h6"]

module.exports = plugin

function plugin () {
  return transform
}

function transform (tree) {
  visit(
    tree,
    node => node.tagName === "section",
    update
  )
}

function update (section) {
  if (section.children && section.children[0] && HEADINGS.includes(section.children[0].tagName)) {
    const heading = section.children[0]
    const { id, ...rest } = heading.properties
    section.properties.id = id
    heading.properties = rest
  }
}

var unified = require("unified") // unified is the text processing interface that powers remark and rehype

var processor = unified()
  .use(require("remark-parse")) // parse markdown text to an AST
  .use(require("remark-sectionize")) // wraps stuff in sections (transforming the AST)
  .use(require("remark-rehype")) // convert the markdown AST to an HTML AST
  .use(require("rehype-slug")) // adds `id` attributes to headings
  .use(require('./rehype-heading-ids-to-section-ids.js')) // the filename for the above plugin code
  .use(require("rehype-stringify")) // convert the modified HTML AST to a string

var outputHTML = processor.process(inputMarkdown)