sync_node_html_to_form_field.js

// keeps the value of formfield set to html contents below target 
window.sync_node_html_to_form_field = function(node, field) {
  var observer = new MutationObserver(function(mutations) {
      field.value = node.innerHTML;
  });
  observer.observe(node, { characterData: true, childList: true, subtree: true });
}