why-cant-we-deploy-today/js/utils/color.js

/**
 * Converts various color input formats to an {r:0,g:0,b:0} object.
 *
 * @param {string} color The string representation of a color
 * @example
 * colorToRgb('#000');
 * @example
 * colorToRgb('#000000');
 * @example
 * colorToRgb('rgb(0,0,0)');
 * @example
 * colorToRgb('rgba(0,0,0)');
 *
 * @return {{r: number, g: number, b: number, [a]: number}|null}
 */
export const colorToRgb = (color) => {
  let hex3 = color.match(/^#([0-9a-f]{3})$/i);
  if (hex3 && hex3[1]) {
    hex3 = hex3[1];
    return {
      r: parseInt(hex3.charAt(0), 16) * 0x11,
      g: parseInt(hex3.charAt(1), 16) * 0x11,
      b: parseInt(hex3.charAt(2), 16) * 0x11,
    };
  }

  let hex6 = color.match(/^#([0-9a-f]{6})$/i);
  if (hex6 && hex6[1]) {
    hex6 = hex6[1];
    return {
      r: parseInt(hex6.slice(0, 2), 16),
      g: parseInt(hex6.slice(2, 4), 16),
      b: parseInt(hex6.slice(4, 6), 16),
    };
  }

  let rgb = color.match(/^rgb\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\)$/i);
  if (rgb) {
    return {
      r: parseInt(rgb[1], 10),
      g: parseInt(rgb[2], 10),
      b: parseInt(rgb[3], 10),
    };
  }

  let rgba = color.match(
    /^rgba\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\,\s*([\d]+|[\d]*.[\d]+)\s*\)$/i
  );
  if (rgba) {
    return {
      r: parseInt(rgba[1], 10),
      g: parseInt(rgba[2], 10),
      b: parseInt(rgba[3], 10),
      a: parseFloat(rgba[4]),
    };
  }

  return null;
};

/**
 * Calculates brightness on a scale of 0-255.
 *
 * @param {string} color See colorToRgb for supported formats.
 * @see {@link colorToRgb}
 */
export const colorBrightness = (color) => {
  if (typeof color === "string") color = colorToRgb(color);

  if (color) {
    return (color.r * 299 + color.g * 587 + color.b * 114) / 1000;
  }

  return null;
};