validate-hex-color.js

  /**
   * Validates hex value
   * @param  {String} color hex color value
   * @return {Boolean}
   */
  function isValidHex(color) {
    if(!color || typeof color !== 'string') return false;

    // Validate hex values
    if(color.substring(0, 1) === '#') color = color.substring(1);

    switch(color.length) {
      case 3: return /^[0-9A-F]{3}$/i.test(color);
      case 6: return /^[0-9A-F]{6}$/i.test(color);
      case 8: return /^[0-9A-F]{8}$/i.test(color);
      default: return false;
    }

    return false;
  }