function image() {
};

image = new image();
number = 0;

image[number++] = "<img src='images/index-photo-01.jpg' width='750' height='155'>"
image[number++] = "<img src='images/index-photo-02.jpg' width='750' height='155'>"
image[number++] = "<img src='images/index-photo-03.jpg' width='750' height='155'>"
image[number++] = "<img src='images/index-photo-04.jpg' width='750' height='155'>"
image[number++] = "<img src='images/index-photo-05.jpg' width='750' height='155'>"

increment = Math.floor(Math.random() * number);

document.write(image[increment]);