Simple Event Handling and Processing

Clicking in the blue box will pop up a "Hello World!" alert window. Clicking on the first link will take you to the YUI website; clicking on the second link, which has the same href attribute, will pop up an alert instead and not navigate to a new page.

Event Utility is used here to do two things:

1. Attach the click event handler to the blue box;
2. Attach an event handler to the second <a> element that uses YAHOO.util.Event.preventDefault() to prevent the link, when clicked, from navigating to a new page.