Introduction to Dynamic HTML
August 24, 1998
Dynamic HTML builds upon existing HTML standards to expand the
possibilities of Web page design, presentation, and interaction.
Ultimately, mastering DHTML will allow you to build Web-based
applications, rather than mere portraits of data.
Because DHTML is essentially an "added
value" technology, you should be rather familiar
with basic Web page design using traditional HTML specifications.
Experience with JavaScript programming is also
necessary to employ the potential of DHTML. Consequently, portions
of this introduction to DHTML will assume some
HTML and
JavaScript familiarity.
What and Why
The Web is an ever evolving environment, and Web pages themselves are
steadily blooming from static displays of
data to interactive applications. "Dynamic HTML" is somewhat
of an umbrella term encompassing several
ways in which Web developers can breathe life into pages which have
traditionally been still portraits of information.
The basic notion behind Dynamic HTML is quite simple: allow any
element of a page to be changeable at any time.
Sounds like a dream, but as with any simple plan, "God is in
the details," as they say. In the olden
days, you could only change content on a page via
CGI. This
required a server to perform the changes to the page
and re-serve the entire page, modifications and all, back to
the client. While workable, this process was quite
slow, as it placed a burden on both network traffic and server
processing time. With long delays between a user's
action and an on-screen response, building effective Web-based
applications was quite constricting.
With DHTML, the magic occurs entirely on the client-side. This means
that page modifications should appear immediately
following a trigger, such as a user selection. And, remember, the
DHTML dream is that you can modify any aspect
of the currently loaded page -- text styles, swapped images,
context-sensitive forms and tables, and even the on-screen
data itself.
It's worth noting here, then, that "Dynamic HTML," isn't
really about HTML, the markup language. By
and large, DHTML describes the abstract concept of breaking up a
page into manipulable elements, and exposing those
elements to a
scripting
language which can perform the manipulations.
The degree, or fineness, to which these elements
are defined and actionable is a function of DHTML's maturity. And
since it has only been around for a year or so,
DHTML is not fully mature.
Like the Web itself, Dynamic HTML is ever evolving. At some point,
DHTML may self actualize and reach its full
potential of "change anything anywhere anytime." It may
even change its name -- product developers possess
a whimsy for this sort of thing -- but the concepts defined above
for modifying elements on a page will necessarily
continue to mature.
Contents:
Introduction to Dynamic HTML
Introduction to Dynamic HTML: The Old Standard about Standards
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