get-md.js

import markdownIt from 'markdown-it'
import markdownItFootnote from 'markdown-it-footnote'
import markdownItEmoji from 'markdown-it-emoji'
import markdownItHighlightjs from 'markdown-it-highlightjs'
// @ts-ignore
import markdownItSub from 'markdown-it-sub'
// @ts-ignore
import markdownItSup from 'markdown-it-sup'
// @ts-ignore
import markdownItDeflist from 'markdown-it-deflist'
// @ts-ignore
import markdownItIns from 'markdown-it-ins'
// @ts-ignore
import markdownItMark from 'markdown-it-mark'
// @ts-ignore
import markdownItAbbr from 'markdown-it-abbr'
import Handlebars from 'handlebars'

const mdOpts = {
  html: true,
  linkify: true,
  typographer: true
}

export function getMd () {
  const md = markdownIt(mdOpts)
    .use(markdownItSub)
    .use(markdownItSup)
    .use(markdownItFootnote)
    .use(markdownItDeflist)
    .use(markdownItEmoji)
    .use(markdownItIns)
    .use(markdownItMark)
    .use(markdownItAbbr)
    // @ts-ignore These @types suck! This works fine.
    .use(markdownItHighlightjs, { auto: false, code: true })

  // disable autolinking for filenames
  md.linkify.tlds('.md', false) // markdown
  return md
}

/**
 * Renders markdown, and accepts an optional markdown-it instance
 * @param  {string} mdUnparsed unparsed markdown
 * @param  {object} vars to expose to handlebars
 * @param  {markdownIt} [md]         an instance of markdown
 * @return {string}            Rendered markdown to html
 */
export function renderMd (mdUnparsed, vars, md) {
  if (!md) md = getMd()
  const template = Handlebars.compile(mdUnparsed)
  const body = rewriteLinks(md.render(template(vars)))
  return body
}

/**
  * Rewrites relative `$1.md` and `$1.markdown` links in body to `$1/index.html`.
  * If pretty is false, rewrites `$1.md` to `$1.html`.
  * `readme.md` is always rewritten to `index.html`. From sitedown
  *
  * @param  {String} body - html content to rewrite
  * @return {String}
  */
function rewriteLinks (body /*, pretty */) {
  body = body || ''

  // if (pretty !== false) pretty = true // default to true if omitted

  const regex = /(href=")((?!http[s]*:).*)(\.md|\.markdown)"/g

  return body.replace(regex, function (_match, p1, p2, _p3) {
    const f = p2.toLowerCase()

    // root readme
    if (f === 'readme') return p1 + '/"'

    // nested readme
    if (f.match(/readme$/)) return p1 + f.replace(/readme$/, '') + '"'

    // pretty url
    // if (pretty) return p1 + f + '/"'

    // default
    return p1 + p2 + '.html"'
  })
}