favorite-fish.js

/**
* Paste the following block into your dev console to average the colors of your favorite fish
* and assign it as your block color (temporarily) : ) 💜🐟
* Bookmarklet: http://duskjacket.com/static/fav-fish/
**/

(function () {
  const dec2hex = function (v) { return v.toString(16);};
  const hex2dec = function (v) { return parseInt(v, 16);};
  const friends = document.querySelectorAll('#friends a');
  let hex = 0;
  var rgb = [0, 0, 0];
  for (i =0; i < friends.length; i++) {
    const friend = friends[i];
    const c = friend.style.backgroundColor;
    /* annoying but sometimes devtools converts hex to rgb so need to account for this */
    if (c.startsWith('rgb')) {
      const pc = c.match(/rgb\((\d+), (\d+), (\d+)\)/);
      rgb[0] += parseInt(pc[1], 10); rgb[1] += parseInt(pc[2], 10); rgb[2] += parseInt(pc[3], 10);
    } else {
      hex += hex2dec(friend.style.backgroundColor);
    }
  }

  let final;
  if (hex !== 0) {
    const avgHex = dec2hex(Math.round(avg/friends.length));
    final = `#${avgHex}`;
    console.log(final);
  } else {
    final = `rgb(${Math.round(rgb[0]/friends.length)}, ${Math.round(rgb[1]/friends.length)}, ${Math.round(rgb[2]/friends.length)})`;
    console.log(final);
  }
  document.querySelector('.box.large').style.backgroundColor = final;
})();