// JavaScript Document

function image() {
};

image = new image();
number = 0;

// imageArray
image[number++] = "<img src='images/logo_main.png' alt='image' />"
image[number++] = "<img src='images/logo_main_1.png' alt='image1' />"
image[number++] = "<img src='images/logo_main_2.png' alt='image2' />"
image[number++] = "<img src='images/logo_main_3.png' alt='image3' />"
// keep adding items here...

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

document.write(image[increment]);