JavaScript: The Definitive Guide, Fourth Edition

DHTML in Fourth-Generation Browsers

Internet Explorer 4 and Netscape 4 were the browsers that introduced DHTML technology to the Internet. Both browsers include partial support for the CSS1 standard and support the CSS positioning attributes (which were integrated into the CSS2 standard) that are critical to DHTML. Unfortunately, the DOM standard did not exist when these fourth-generation browsers were being developed, so they do not conform to that standard. Nevertheless, it is possible to achieve DHTML effects in both browsers.

DHTML in Internet Explorer 4

As we saw in Chapter 17, IE 4 does not support the document.getElementById( ) method, nor does it support an API for dynamically creating new nodes and inserting them into a document. Instead, it provides the document.all[] array as a way of locating arbitrary elements of the document and allows document content to be altered with the innerHTML property of document elements. IE 4 does not conform to the standards here, but it provides adequate alternatives.

Although traversing and modifying documents is an important part of DHTML, the focus of this chapter is on the dynamic use of CSS styles. The good news is that the DOM API described earlier for setting CSS style attributes through the style property was adopted from the IE 4 API. Thus, once you’ve used document.all[] to locate the document element you want to modify, you can script the styles of that element just as you would in a browser that fully supports the DOM API. ...