var theImages = new Array() // do not change this
theImages[0] = 'Images/1.jpg';
theImages[1] = 'Images/2.jpg';
theImages[2] = 'Images/3.jpg';
theImages[3] = 'Images/4.jpg';
theImages[4] = 'Images/5.jpg';
theImages[5] = 'Images/6.jpg';
var p = theImages.length;
var preBuffer = new Array()
for (i = 0; i < p; i++) {
    preBuffer[i] = new Image()
    preBuffer[i].src = theImages[i]
}
var whichImage = Math.round(Math.random() * (p - 1));
document.getElementById("bannerImage").src = theImages[whichImage];