Once a web server processes a web page and sends it to the computer
requesting it (called the 'Client' computer) it cannot get any
more data from the server unless a new request is made. So to
move around this drawback we use Dynamic HTML (DHTML) which is
combining HTML and a scripting language that runs on the Client's
browser to bring special effects to otherwise static pages. The
browsers support it. The scripting language can be used to alter
HTML data shown (or present but hidden) on the current page by
manipulating the properties for the HTML tags involved. Basically
some script function is called to execute the required effect
when events like 'MouseOver', 'MouseOut', 'Click', etc. occur.
The major examples of DHTML are as follows :
- Using Layers : All the data
to ever be displayed is loaded into the existing pages in HTML
format but is hidden by using the visibility property of HTML
layer elements like LAYER, DIV, etc. Now when an event like
layer. The layer is then hidden on Mouse Out event.
- Using Image Rollovers and Swaps
: If you have some knowledge of web designing then you
should know that when creating Image rollovers or image Swaps
you usually take some script and include it to the content of
your HTML pages. If you look carefully at the HTML code for
the images you will find that they call functions on MouseOver
and MouseOut events.
- Using Dynamic Forms : While
surfing you must have noticed how some forms seem to have special
functions like (a) validation of fields (b) text box character
limits (c) dynamic displayed lists depending on your selection
(d) redirection to other pages (e) manipulating your keyboard
input or disabling some keys or browser buttons, etc. Well all
this is done through calling some corresponding script functions.
- Using Cascading Style Sheets (CSS)
: Yes, you might be surprised to know that CSS is part
.css which is necessary for it to be recognized by the server
and tools like Macromedia's Dreamweaver to contain styles.