imghomeon = new Image();
imghomeon.src = "images/square_on.gif";
imghomeoff = new Image();
imghomeoff.src = "images/square_off.gif";

imgcontacton = new Image();
imgcontacton.src = "images/square_on.gif";
imgcontactoff = new Image();
imgcontactoff.src = "images/square_off.gif";

imgportfolioon = new Image();
imgportfolioon.src = "images/square_on.gif";
imgportfoliooff = new Image();
imgportfoliooff.src = "images/square_off.gif";

// links image functions
function imgAct(imgName) {
    document[imgName].src = eval(imgName + "on.src");
}

function imgInact(imgName) {
    document[imgName].src = eval(imgName + "off.src");
}