code: function ( color ) {
              var type = this.type( color, 'color.toHex() : "' + color + '" ' + MSG_NOT_COLOR );
      
              switch ( type ) {
                  case 'hex':
                      return color;
                      break;
                  case 'rgb':
                  case 'rgba':
                      return this.rgbToHex( color );
                      break;
                  case 'hsl':
                  case 'hsla':
                      color = this.hslToRgb( color );
                      return this.rgbToHex( color );
                      break;
                  case 'keyword':
                      return this.keyword( color, 'color.toHex() : "' + color + '" ' + MSG_NOT_COLOR );
                      break;
              }
          }
docs: Color문자열 ("hex", "rgb", "rgba", "hsl", "hsla", "keyword")을 Hex문자열로 변환하여 반환.
  @param	{String}	color		Color문자열
  @return	{String}