var Mouser =
{
    init: function() {
        var links = Mouser.getElementsByClassName("navImg");
        
        for (var i = 0, ii = links.length; i < ii; i++) {
            links[i].onmouseover = Mouser.mouseOverListener;
            links[i].onmouseout = Mouser.mouseOutListener;
        }
    },
    
    getElementsByClassName: function (className) {
        // Get a list of ALL elements in the document
        if (document.all) {
            var allElements = document.all;
        }
        else {
            var allElements = document.getElementsByTagName("*");
        }
        
        var foundElements = [];
        
        for (var i = 0, ii = allElements.length; i < ii; i++) {
            if (allElements[i].className == className) {
                foundElements[foundElements.length] = allElements[i];
            }
        }
        
        return foundElements;
    },
    
    mouseOverListener: function() {
        var altTag = this.alt;
        var picUrl = "images/" + altTag.toLowerCase() + "-mo.png";
        this.src = picUrl;
    },

    mouseOutListener: function() {
        var altTag = this.alt;
        var picUrl = "images/" + altTag.toLowerCase() + ".png";
        this.src = picUrl;
    }
};

Mouser.init();