window.onload = initRollovers;

function initRollovers() {
    if (!document.getElementsByTagName) { return; }
    var anchors = document.getElementsByTagName("a");
    
    for (var i=0; i<anchors.length; i++) {
        var anchor = anchors[i];
        
        if (anchor.getAttribute("href") && (anchor.getAttribute("rel") == "swapimage")) {
            anchor.onmouseover = function() { imageSwap(this); return false; }
            anchor.onmouseout = function() { imageBack(this); return false; }
        }
    }
}

function imageSwap(anchor) {
    var linkimg = anchor.childNodes[0];
    var originalfilename = linkimg.src;
    var extensionpos = originalfilename.lastIndexOf('.');
    var filenamestart = originalfilename.lastIndexOf('/');
    var extension = originalfilename.substring(extensionpos+1, originalfilename.length);
    linkimg.src = originalfilename.substring(0, extensionpos) + "-hover." + extension;
    
}

function imageBack(anchor) {
    var linkimg = anchor.childNodes[0];
    var originalfilename = linkimg.src;
    if (originalfilename.indexOf('-hover') != -1) {
	    var extensionpos = originalfilename.lastIndexOf('-hover');
	    var filenamestart = originalfilename.lastIndexOf('/');
	    var extension = originalfilename.substring(extensionpos+7, originalfilename.length);
	    linkimg.src = originalfilename.substring(0, extensionpos) + "." + extension;
	}
}