twitter-contest.js

!function() {
  // Don't forget to scroll all the way down to load all replies!
  
  const elems = document.body.querySelectorAll(
    'div.original-permalink-page ' +
      'li.ThreadedConversation:not(.ThreadedConversation--selfThread),' +
      'li.ThreadedConversation--loneTweet');

  for (const elem of elems) {
    elem.style.border = '2px solid green';
    elem.style['transition'] = 'border 1s';
  }

  const index = Math.floor(Math.random() * elems.length);

  const styles = [
    '4px solid red',
    '4px solid yellow',
  ];
  let iteration = 0;

  function swap() {
    elems[index].style.border = styles[iteration];
    iteration = (iteration + 1) % styles.length;

    setTimeout(swap, 500);
  }

  swap();
}();