var imageArr = new Array();
        
function PreloadImages(index, imgSrc) {
    imageArr[index] = new Image();
    imageArr[index].src = imgSrc;
}
                
function ShowImage(index) {
    var objImage = document.getElementById("imgFocus");
    if(imageArr[index] != null) {
        objImage.src = imageArr[index].src;
    }
}