If you have experience working with Web pages, you may have noticed that there never seems to be enough room in the browser. With all those tables, images, frames, and text there's hardly any space left for the advertisements that you may depend on to keep your site running. While designing the Center Park Web site, imagine that over a dozen student organizations come to you requesting space on the main page of the site. Obviously, you can't accommodate all of them—at least not at the same time.
Fortunately for you, Internet Explorer allows a Web page to change its content on-the-fly, through the use of the innerHTML property. You immediately started devising a way to rotate separate text advertisements each time a page loads. You can see how the code listing below is reflected in Figures 19.1 and 19.2, as the announcements are different between the two figures.
As stated here, this example is for use only within Internet Explorer.
Each time it loads, this page will choose a random advertisement from a list of predefined advertisements and display it in the table.