Scroll To and Highlight First Empty Radio.user.js

// ==UserScript==
// @name         Scroll To and Highlight First Empty Radio
// @namespace    https://github.com/Kadauchi
// @version      1.0.0
// @description  Scrolls to and highlights the first empty radio on a keypress
// @author       Kadauchi
// @include      *
// ==/UserScript==

const key = '`'; // Go to http://keycode.info/ and press a key to change (you want event.key)

function scrollToAndHighlightEmptyRadio() {
  const radios = document.querySelectorAll('input[type="radio"]');
  const radioGroupNames = [...radios].reduce((names, radio) => names.includes(radio.name) ? names : [...names, radio.name], []);
  const radioGroupEmpty = radioGroupNames.find((name) => !document.querySelector(`input[type="radio"][name="${name}"]:checked`));

  if (radioGroupEmpty) {
    const firstRadioInGroup = document.querySelector(`input[type="radio"][name="${radioGroupEmpty}"]`);
    firstRadioInGroup.scrollIntoView();
    firstRadioInGroup.parentElement.style.backgroundColor = 'red';
  }
}

document.addEventListener('keydown', (event) => {
  if (event.key === key) {
    scrollToAndHighlightEmptyRadio();
  }
});