Java Reference
In-Depth Information
Chapter 10
Exercise 1 Question
Create a web page with an advertisement image at the top. When the page loads, select a random image
for that advertisement. Every four seconds, make the image change to a different one and ensure a dif-
ferent advertisement is selected until all the advertisement images have been seen.
Exercise 1 Solution
The solution below displays three images but changes them via a timer:
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN”
“http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>
<html xmlns=”http://www.w3.org/1999/xhtml”>
<head>
<script type=”text/javascript”>
var imagesSelected = new Array(false,false,false);
var noOfImages = 3;
var totalImagesSelected = 0;
function window_onload()
{
setInterval(“switchImage()”,4000);
}
function switchImage()
{
var imageIndex;
if (totalImagesSelected == noOfImages)
{
for (imageIndex = 0; imageIndex < noOfImages; imageIndex++)
{
imagesSelected[imageIndex] = false;
}
totalImagesSelected = 0;
}
var selectedImage = Math.floor(Math.random() * noOfImages) + 1;
while (imagesSelected[selectedImage - 1] == true)
{
selectedImage = Math.floor(Math.random() * noOfImages) + 1;
}
totalImagesSelected++;
imagesSelected[selectedImage - 1] = true;
