Conversion de couleur

function rgbToHex(r, g, b) {
  return "#" + [r, g, b].map(x => x.toString(16).padStart(2, "0")).join("");
}

function hexToRgb(hex) {
  const m = hex.replace("#", "").match(/.{2}/g);
  return m ? m.map(x => parseInt(x, 16)) : null;
}

function hexToRgba(hex, alpha = 1) {
  const [r, g, b] = hexToRgb(hex);
  return `rgba(${r},${g},${b},${alpha})`;
}