Find used colors on page

find_color.js

function colorCount() {
  function trim(str) {
    return str.replace(/^\s+|\s+$/gm, '');
  }

  function toComponents(str) {
    return str.match(/rgba?\((.+)\)/)[1].split(',').map(s => s.trim()).map(s => parseInt(s, 10))
  }

  function componentToHex(c) {
    var hex = c.toString(16);
    return hex.length == 1 ? '0' + hex : hex;
  }

  function rgbToHex(r, g, b) {
    return ('#' + componentToHex(r) + componentToHex(g) + componentToHex(b)).toUpperCase();
  }

  function rgbaToHex(rgba) {
    const components = toComponents(rgba);
    return rgbToHex.apply(null, components)
  }
  const colors = Array.from(document.querySelectorAll('*')).reduce(
    (agg, node) => {
      const style = window.getComputedStyle(node);
      const fg = rgbaToHex(style.color);
      const bg = rgbaToHex(style.backgroundColor);
      for (const c of [fg, bg]) {
        if (agg[c] > 0) {
          agg[c] += 1;
        } else {
          agg[c] = 1;
        }
      }
      return agg;
    },
    {}
  );
  const colorList = Object.keys(colors).map(color => [color, colors[color]]);
  colorList.sort((a, b) => (a[1] > b[1] ? -1 : b[1] > a[1] ? 1 : 0));
  return colorList.map(val => val[0] + ': ' + val[1]).join('\n');
}