Advanced Features

Netscape introduced frames in their version 2.0 browser, and later versions of the Microsoft browser can handle frames. Frames allow the users to simultaneously view separate files on their browsers. The site designer specifies the pages and images the user receives, and the size of each as displayed on the user's monitor.

Not every web site should use frames. Frames offer several advantages, such as being able to constantly display a menu for easy navigation through the site. However, one of several disadvantages is that pages are displayed in a smaller area of the screen.

As with most other design considerations, the pros and cons of using frames for a particular site must be weighted to ensure that the best choice is made. If frames are used, a non-frame alternative should be provided not just for visitors whose browsers do not support frames, but also for those users who do not wish to have frames. For example the page titled Site Design Considerations provides both a frame and non-frame option for viewing.

Java Applets have become quite popular on web sites now. An applet is a small application (program) embedded in the web page. Some of the ways applets are commonly used are: Animations, scrolling messages, clickable maps, input and output forms. Since an applet is an embedded program, any purpose served by other types of programs can be served by an applet, but an applet is not able to read from or write to a user's hard drive (a security measure).

Applets can be quite useful to a web page, however the page must provide alternatives if needed for a user whose browser does not support Java (or has Java turned off). An applet that is only used for decoration does not need alternative content, but where the applet is referenced or used for presenting content, then the alternative content needs to be incorporated. Incorporating alternative content is simply a matter of adding text and HTML markup (code) within the markup for the applet.

ActiveX controls are commonly thought of as Microsoft's answer to Java applets. This is not really the case. The ActiveX controls have been used in other Microsoft applications, and are now supported by Microsoft's Internet Explorer. Most of the uses of ActiveX controls can be handled by Java applets. Since the applets are more widely supported by web browsers, a function that can be handled by either the applet or the control, would probably be better supported by using a Java applet.

Client-side scripting is the inclusion of lines of code in the web page that provide additional functionality and presentation to the page. One of the best uses of client-side script is verification of user input to a form. Instead of having to send the input to the server to have the input checked and then have any error messages sent back to the user, the client-side script can check the input before it is sent, thus reducing on network and server load.

Two client-side scripting languages employed are VB Script and JavaScript. VB Script is derive from Visual Basic and is supported by Microsoft. JavaScript was implemented Netscape, and is now somewhat supported by Microsoft (through a version called JScript). Though JavaScript is more widely supported, care is needed since there are incompatibilities between the various versions (especially with JScript).

The client-side scripting can serve a variety of functions from verifying user input to controlling the display of a page, even to allow for entirely different presentations of the same page. User controlled slide shows, control of frames, calculations on the page, are some other functions for which scripting can be used.

Though many pages can benefit from the use of client-side scripting it is important that the pages do not solely rely on the scripts. Not all users have browser capable of interpreting the scripts, and other users may have scripting support turned off on their browsers. Users without client-side script support should be backed up by a server-side script for form verifications, calculations, and other processing type applications.

There are a number of other new features available. The examples above show that caution needs to be exercised with many of the new features. With some of the features care needs to be exercised to ensure all users receive a clear and presentable version of the page. Others must be avoided, at least for now.

A skilled designer will be able to design the pages for the best presentation using many advanced feature, while maintaining the presentation for all users regardless of which browser they use.

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