Bookmarklet to create a window and resize it multiple times (for condensing breakpoint screenshots into gifs)

resize.js

(function() {
  const bg = document.createElement('div');
  bg.style.position = 'absolute';
  bg.style.top = '0';
  bg.style.width = '100%';
  bg.style.height = '100%';
  bg.style.background = '#000';
  bg.style.zIndex = '99999';
  document.body.appendChild(bg);
  
  const widths = [375, 552, 728, 904, 1080];
  const num = widths.length;
  const h = window.outerHeight;
  const win = window.open(location.href, 'resize',
    `left=5,top=0,width=${widths[0]},height=${h}`);
  setTimeout(() => {
    widths.forEach((w, i) => setTimeout(() => win.resizeTo(w, h), 1000 * i));
    setTimeout(() => bg.remove(), 1000 * num);
  }, 5000);
}());