HTML and CSS Reference
In-Depth Information
Originally termed “DHTML” (dynamic HTML), such kludges have more recently
been handled in better ways using JavaScript libraries and the like. But the fact still
remains that they are kludges for the following reasons:
No better semantic elements are available to use for implementing features
like video and complex form controls. The markup for such things tends to
consist of loads of unsemantic nested
<div>
is and so forth. There is therefore
no way for screen readers, search engines, or other automated user agents to
work out what these constructs are supposed to be (although WAI-ARIA can
help mitigate such problems), which is a problem for SEO and accessibility.
Such implementations tend to add a significant amount of weight to the page.
These kludges are used to create very common use cases: It seems ridiculous
for you to have to resort to hacks and overcomplicated custom implementa-
tions to implement them.
HTML5 comes to the rescue in these regards while maintaining backward
compatibility. It includes all of the features already available in HTML 4, plus it
defines previously missing details and adds several new features into the mix for
creating applications, such as:
New semantic elements for defining common page regions, such as headers,
footers, primary navigation, distinct articles of content, figures, and so on.
<canvas>
and its associated API for creating complex scripted graphics,
like animations.
<audio>
,
<video>,
and associated APIs for working with AV content.
Mechanisms for allowing applications to work o
ine.
Error handling to define what should happen when badly formed markup
is used (missing closing tags, etc.)
