RGB conversion implementation code, written test questions for Taobao front-end development engineer

function RGB(rgb)
{
reg=/^#([a-fA-F0-9]{2})([a-fA-F0-9]{2})([a-fA-F0-9]{2})$/;
if ( (rgb) )
rgb='rgb('+parseInt(RegExp.$1,16)+","+parseInt(RegExp.$2,16)+","+parseInt(RegExp.$3,16)+')';
return rgb;
}