A derivative of https://gist.githubusercontent.com/foolip/f60a1614fb5d194aad4dbff89c54ceb3/raw/9aa4dedbf78b7dbff3805d9f7b6aff953fe93b5d/convert.html to help with fetch conversion

convert-to-bikeshed.html

<meta charset=utf-8>
<textarea style="width: 100%; height:100%"></textarea>
<script>
function stripIntro(doc) {
  while (doc.body.firstChild.id != 'goals')
    doc.body.firstChild.remove();
}
function anolisToBikeshed(doc) {
  // remove all internal markup from IDL blocks
  for (let idl  of [].slice.call(doc.body.querySelectorAll('pre.idl'))) {
     idl.textContent = idl.textContent;
  }
  var index =  {};
  for (let e of [].slice.call(doc.body.querySelectorAll('dfn'))) {
     if (e.hasAttribute("title")) {
         const value = e.getAttribute("title");
         if (value.startsWith('concept-')) {
           e.id = value;
           const comps = value.split('-');
           var target;
           if (comps.length > 2) {
               target = comps.slice(1, comps.length -1).join("-");
               e.setAttribute("for", target);
           }
           index[value] = { text: e.textContent};
           if (target) {
                index[value]["for"]= target;
           }
         }
      }
  }
  for (let e  of [].slice.call(doc.body.querySelectorAll('span[data-anolis-ref]'))) {
          var informative = e.classList.contains("informative");
          var text = document.createTextNode('[['+ (informative ? '' : '!') + e.textContent + ']]');
          e.parentNode.replaceChild(text, e);
  }
  // TODO: the same for <code data-anolis-spec>
  for (let e  of [].slice.call(doc.body.querySelectorAll('span[data-anolis-spec]'))) {
      let a = doc.createElement('a');
      const attributeNames = [].map.call(e.attributes, a => a.name);
      for (let name of attributeNames) {
        if (name == "title") continue;
        if (name == "data-anolis-spec") {
           a.setAttribute("spec", e.getAttribute(name));
           continue;
        }
        a.setAttribute(name, e.getAttribute(name));
      }
      while (e.firstChild)
        a.appendChild(e.firstChild);
      e.parentNode.replaceChild(a, e);
  }

  // loop over and transform all elements/attributes
  const elements = [].slice.call(doc.body.querySelectorAll('*'));
  for (let e of elements) {
    const attributeNames = [].map.call(e.attributes, a => a.name);
    if (e.localName == 'span' && !e.classList.contains('note')) {
      // <span> => <a>
      let a = doc.createElement('a');
      for (let name of attributeNames)
        a.setAttribute(name, e.getAttribute(name));
      while (e.firstChild)
        a.appendChild(e.firstChild);
      e.parentNode.replaceChild(a, e);
      e = a;
    }
    for (let name of attributeNames) {
      const value = e.getAttribute(name);
      switch (name) {
        case 'title':
          if (value) {
            if (e.localName == 'code') {
              // wrap in <a>, Bikeshed doesn't autolink <code>
              var a = doc.createElement('a');
              e.parentNode.replaceChild(a, e);
              a.appendChild(e);
            }  else if (e.localName == 'dfn') {
            }  else {
              if (value.startsWith('concept-')) {
                if (index[value]) {
                  if (e.textContent.toLowerCase() !== index[value].text) {
                     e.setAttribute('lt', index[value].text);
                  }
                  if (index[value]["for"] && attributeNames.indexOf('data-dfn-for') == -1) {
                     e.setAttribute('for', index[value]["for"]);
                  }
                } else {
                  console.log(value + " not found in index");
                }
                // drop and fix with <pre class=link-defaults>
              // TODO Deal with 'dom-[Interface]-[name]'
              } else {
                // title="foo-bar" -> lt="foo bar"
                const ltValue = value.replace(/-/g, ' ');
                // skip plural forms, Bikeshed understand
                if (e.textContent != ltValue + 's' && e.textContent != ltValue)
                  e.setAttribute('lt', ltValue);
              }
            }
          }
          e.removeAttribute(name);
          break;
      }
    }
  }
}
function serialize(doc) {
  var html = doc.body.innerHTML;
  // strip </p> and similar
  html = html.replace(/<\/(p|li|dd|dt|th|td|tr|thead|tbody)>/g, '');
  // attr="" => attr
  html = html.replace(/=""/g, '');
  // &gt; => >
  html = html.replace(/&gt;/g, '>');
  // attr="no-whitespace" => attr=no-whitespace
  html = html.replace(/="([^ ]+)"/g, '=$1');
  return html;
}
document.querySelector('textarea').addEventListener('paste', event => {
  setTimeout(() => {
    const input = event.target.value;
    var parser = new DOMParser();
  var doc = parser.parseFromString(input, "text/html");
  console.log(doc);
    stripIntro(doc);
    // if anolisToBikeshed() is skipped, there are no interesting differences
    anolisToBikeshed(doc);
    var output = serialize(doc);
    event.target.value = output;
    event.target.select();
  }, 0);
});
</script>