application.js

function rgb2hex(rgb) {
  rgb = rgb.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/);
  function hex(x) {
      return ("0" + parseInt(x).toString(16)).slice(-2);
  }
  return "#" + hex(rgb[1]) + hex(rgb[2]) + hex(rgb[3]);
}