Image Background Color

Sets a checkerboard (or color) background on images viewed standalone.

// ==UserScript==
// @name        Image Background Color
// @namespace   leaumar
// @match       *://*/*
// @grant       none
// @version     2
// @author      [email protected]
// @description Sets a checkerboard (or color) background on images viewed standalone.
// @license     MPL-2.0
// @icon        data:image/png;base64,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
// ==/UserScript==

const checkerBoard = {
  backgroundColor: 'darkgrey',
  backgroundImage: 'linear-gradient(45deg, grey 25%, transparent 25%, transparent 75%, grey 75%, grey), linear-gradient(45deg, grey 25%, transparent 25%, transparent 75%, grey 75%, grey)',
  backgroundPosition: '0 0, 2vmin 2vmin',
  backgroundSize: '4vmin 4vmin',
};

function setBackground(node) {
  Object.assign(node.style, checkerBoard);
  // or assign a fixed color if you want
  // node.style.backgroundColor = '#333';
}

function getStandaloneImage() {
  const tags = [...document.body.childNodes]
    .filter(node => node.nodeName !== '#text');

  return tags.length === 1 && tags[0].nodeName === 'IMG' ? tags[0] : null;
}

function clearAllBackgrounds(upFrom) {
  let current = upFrom;
  while (current?.style != null) {
    current.style.background = 'unset';
    current = current.parentNode;
  }
}

(function main() {
  const img = getStandaloneImage();
  if (img != null) {
    clearAllBackgrounds(img);
    setBackground(document.body);
  }
})();