var ns4 = (document.layers);
var ie = (document.all);
var ns6 = (!document.all && document.getElementById);


if (document.images) {
  
  // menu
  image1on = new Image();
  image1on.src = "images/home-on.jpg"; 
    
  
  image1off = new Image();
  image1off.src = "images/home-off.jpg"; 

}

function turnOn(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "on.src");
  }
}

function turnOff(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "off.src");
  }
}