Using Behaviors in Java

Print DataMatrix in Java Using Behaviors

FIGURE 8-4

Use the Show Pop-Up Menu behavior to call up a menu of links when the visitor interacts with the trigger element

a 1-second delay, since 1000 milliseconds equals 1 second Having a delay is usually a good idea, since the pop-up menu may partially conceal another clickable element on the page You want to give the visitor the opportunity to click the element before the menu comes up Under the Position tab, choose where the pop-up menu should appear in relation to the trigger element Then fine tune the position by typing values into the X and Y fields To close the menu automatically after the visitor mouses away, check the Hide Menu option Click OK to create the pop-up menu By default, Dreamweaver assigns the onMouseOver event to this behavior You can change this event on onClick or a handful of others in version 40 browsers and up If you checked the Hide Menu option, Dreamweaver automatically added the Hide Pop-Up Menu behavior to your page If you didn t check this option, you can still apply the Hide Pop-Up Menu behavior manually by choosing it from the list that drops-down when you click the plus button on the Behaviors panel

In this chapter, you learned about Dreamweaver behaviors Behaviors are client-side JavaScript functions that perform various useful tricks and tasks A behavior has three components: the trigger, or the element on the page that launches the behavior; the event, or the thing that happens to the trigger to launch the behavior; and the action, or the function that the behavior performs While behaviors can shift some of the processing burden to the visitor s browser, the visitor can disable your behaviors by turning off JavaScript For this reason, I urged you to add noscript content to your page if you decide to use behaviors You learned that the trigger helps to determine what kinds of behaviors you can attach Not all triggers support the same behaviors You also learned that the visitor s browser determines which events can launch the behaviors Early versions of popular browsers offer relatively few events, while more recent versions offer scores of them However, to keep your site cross-browser-compatible, restrict yourself to events commonly supported in version 40 browsers I explained that you can t attach certain events to certain triggers However, Dreamweaver can nest the trigger element between opening and closing anchor tags, thereby giving you a wider selection of events When an event appears in parentheses on the Behaviors panel, you know that Dreamweaver has to nest the trigger between anchor tags and attach the behavior to the anchor, not the trigger itself You then explored the various behaviors that Dreamweaver offers You saw that behaviors can perform marvelous feats, everything from opening pop-up messages and pop-up windows to managing images, checking browsers and plug-ins, validating forms, adding HTML content on the fly, and animating layers In spite of this functional arsenal, I explained why it s usually better to develop your own clientside functions in a professional setting

8:

Working with Triggers, Events, and Actions u A trigger is the element on the page that launches the behavior u An event is the thing that happens to the trigger to launch the behavior u An action is the function that the behavior performs u Not all triggers support the same behaviors u Older browsers generally support few events u In general, Dreamweaver behaviors aren t useful in version 30 browsers u If a trigger has multiple behaviors with the same event, the order in which

your visitors can deactivate all the functions by turning off JavaScript in their browser preferences