LightenDarkenColor

lightenDarkenColor.js

const LightenDarkernColor = (color, amount) => {
  const usePound = color[0] === '#';
  const col = usePound ? color.slice(1) : color;
  const num = parseInt(col, 16);
  let r = (num >> 16) + amount;
  if (r > 255) r = 255;
  else if (r < 0) r = 0;
  let b = ((num >> 8) & 0x00FF) + amount;
  if (b > 255) b = 255;
  else if (b < 0) b = 0;
  let g = (num & 0x0000FF) + amount;
  if (g > 255) g = 255;
  else if (g < 0) g = 0;
  return `${usePound ? '#' : ''}${(g | (b << 8) | (r << 16)).toString(16)}`;
}