headings.js

const crypto = require("crypto");

module.exports = {
  onWillParseMarkdown: function (markdown) {
    return new Promise((resolve, reject) => {
      return resolve(markdown);
    });
  },
  onDidParseMarkdown: function (html, { cheerio }) {
    return new Promise((resolve, reject) => {
       const makeUrl = (name) => {
        return crypto
          .createHash(algorithm || "md5")
          .update(name, "utf8")
          .digest(encoding || "hex");
      };

      
      // get heading tags and add link and id on them
      html = html.replace(
        /(<h[1-6]>)(.*)(<\/h[1-6]>)/gm,
        (whole, p1, p2, p3) =>
          `${p1}<a id="${makeUrl(p2)}" class="anchor" href="#${makeUrl(
            p2
          )}">${p2}</a>${p3}`
      );
      return resolve(html);
    });
  },
  onWillTransformMarkdown: function (markdown) {
    return new Promise((resolve, reject) => {
      return resolve(markdown);
    });
  },
  onDidTransformMarkdown: function (markdown) {
    return new Promise((resolve, reject) => {
      return resolve(markdown);
    });
  },
};