DHTML | DHTML Classes | DHTML FAQ

DHTML (Dynamic HTML)

1. What is DHTML?
2. What is DHTML Script?
3. How does DHTML Script differ from JavaScript?
4. Which browsers support DHTML, and how will non-supporting browsers handle DHTML?
5. How does Dynamic HTML relate to HTML and Cascading Style Sheets?
6. How does Microsoft's implementation of Dynamic HTML compare with Netscape's technology?

DHTML, or Dynamic HTML, is a new web technology that enables elements inside your web page to be, well, dynamic. Things once considered unchangeable once the page has loaded, such as text, page styles (font color, size etc), element position, etc, can now all be changed dynamically, thanks to DHTML. It brings your web pages one step closer to how things look inside your television, where images appear and disappear, text flies in and out, and content move around freely inside the screen.

DHTML scripts are scripts that take advantage of the DHTML technology to bring true interactivity to your site. They can be written in a number of languages, although the most popular are JavaScript and VBscript. All scripts here at Dynamic Drive are written in JavaScript1.2 (the newest version of JavaScript).

Think of DHTML script as an advanced form of JavaScript. While both are written using the JavaScript language, DHTML scripts utilize and access the DHTML features of your fourth generation browser (or later), while JavaScript does not.

Netscape 4+ and Internet Explorer 4+ both support DHTML, although to different extents. IE 4 is more complete in it's support of DHTML, so you will find more scripts for IE 4+ (marked with the IE label beside the script). Regardless of which browser the scripts are written for, all of them are designed to be as compatible as possible to all browsers, including NS 3- and IE 3-. Having said that, you should always test a script on multiple browsers to ensure that it degrades well with all of them.

HTML specifies contextual information and content for a Web page, including headings, forms, tables, paragraphs, links, and more. Cascading Style Sheets (CSS) specify the presentation of this content. Dynamic HTML, through the Document Object Model, provides an object model and API to allow interaction with HTML elements or CSS information.

So, for example, an author uses HTML to specify that there is a table, CSS to control the style/presentation of the table, and Dynamic HTML to update the contents of the table or its presentation.

Both technologies support the W3C CSS Recommendation and CSS Positioning Working Draft . However, Microsoft's and Netscape's technologies fundamentally differ, because Microsoft's implementation of Dynamic HTML, based on the Document Object Model, provides greater creative control than Netscape's implementation of Dynamic HTML, which provides little support for the Document Object Model.

Netscape's version of Dynamic HTML in Navigator 4.0 exposes few page elements as objects, limiting layout and creative capabilities for authors. Page elements can be manipulated only while the page is loading, not after load time. Netscape's nonstandard implementation consists of JavaScript Accessible Style Sheets (JASS), layers, and dynamic fonts (TrueDoc). These technologies are not supported in Microsoft Internet Explorer 4.0.

Microsoft's implementation of Dynamic HTML also includes functionality, such as data binding, that is not supported by Netscape 4.0.

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