var firstImage = 1;
var secondImage = 2;
var lastImage = 20;

var nextImage = "portfolio-"+ (portfolioImage + 1) +".htm";
var previousImage = "portfolio-"+ (portfolioImage - 1) +".htm";

if (portfolioImage == firstImage){var previousImage = "portfolio-"+ lastImage +".htm";}
if (portfolioImage == secondImage){var previousImage = "index.htm";}
if (portfolioImage == lastImage){var nextImage = "index.htm";}

var imageSource = "<img src=\"../img/portfolio/"+portfolioImage+".jpg\" alt=\""+title+"\" />";
var selectedItem = "<style type=\"text/css\">ul#portfolioNav li a#nav"+portfolioImage+" { background: #846d69 url(../img/portfolio/nav-"+portfolioImage+".gif) 0px 0px no-repeat !important; }</style>"
var nextArrow = "<a href=\""+ nextImage +"\" id=\"next\"></a>";
var previousArrow = "<a href=\""+ previousImage +"\" id=\"previous\"></a>";