Custom shortcode syntax for Elder.js

elderjs-shortcode-motivation.md

why you may need to customize shortcode syntax

• elder.js self closing shortcodes look like this: {{foo bar="true"/}}. Note the / at the end is for Elder.js to parse both self closing and content wrapping shortcodes.
• this clashes with other shortcode systems, eg. dev.to, which uses shortcodes that look like this: {% youtube abc123 %}
• in elder.config.js you can customize the start and end shortcode: {%foo bar="true"/%}
• however that / there is non negotiable.
• this is why you need to customize the shortcode syntax

the strategy is, if you use remark to process the text, to write a custom remark plugin to replace specifically this %} ending code of the dev.to shortcode to what Elder.js expects

the plugin source follows below

remark-replace.js

const visit = require("unist-util-visit");

// info used in writing this
// https://github.com/angeloashmore/gatsby-remark-find-replace/blob/master/src/index.js
// https://swizec.com/blog/how-to-build-a-remark-plugin-to-supercharge-your-static-site/

const replacements = {
  ' %}': ` /%}` // the key replacement we are doing
}
// RegExp to find any replacement keys.
const regexp = RegExp(
  '(' +
    Object.keys(replacements)
      .join('|') +
    ')',
  'g',
)

const replacer = (_match, name) => replacements[name]

module.exports =  function plugin(){
  return function transformer(tree) {
    visit(tree, ['text', 'html'], node => {
      const processedText = node.value.replace(regexp, replacer)
      node.value = processedText
    });
  };
}

/*
 * 
 * usage... eg in elderjs markdown plugin
 * 
 */

let _preset = {
  settings: {},
  plugins: [
    // other plugins here
    require('./remark-replace') // the one we wrote above
  ],
}


async function parseMarkdown({filePath, markdown}) {
  var post_vfile = vfile({ path: filePath, contents: markdown });
  const file = await unified()
    .use(_preset) // using the plugins
    .process(post_vfile)
    .catch((err) => {
      console.error(report(post_vfile));
      throw err;
    });
  file.extname = '.html';
  return file.toString();
}

real life usage https://github.com/sw-yx/swyxdotio/blob/2435aeb705f0c9c1e836c8a0f1159f922ee12769/src/plugins/elderjs-plugin-markdown/index.js#L39