| If
you want do more with your web
site's pages than is possible
with html alone, JavaScript is
definitely a programming language
to consider. It's free, does not
require special server support
(since it runs in the user's
browser), and is widely supported
by books, tutorial sites, and
forums. Uses
and Limitations
JavaScript can
be very useful for many tasks
ranging from very simple to
fairly complex. For example:
Javascript
has a variety of date and
time functions. You could
have Javascript calculate the
date, the time, the day of
the month, or that today is
TargetField
perhaps
adding some related text, as
appropriate. (If, by some
chance, the preceding
sentence does not
refer to the correct day of
the week, it's probably
because (1) your computer's
clock is not set to the right
date, (2) you don't have
Javascript enabled in your
browser, or (3) you are using
a browser which does not
support the date functions I
used.)
Javascript
can be used to create simple
games, such as the trivia
games which I've made
available on this page. Of course, you can
also use it to create more
complex games.
Javascript
has various graphics
functions. You could use it
to display a random picture
or for something more
intricate, such as The JavaScript
Raytracer. In addition to
being an impressive
demonstration of the type of
program that JavaScript is
capable of, it's worth taking
a peek at the source code of
this application to gain some
insight into how to use
JavaScript for advanced
graphics programming (and how
ray tracers work).
Of course, like
every programming language,
JavaScript has its limitations.
Among them:
Javascript
can not write data to either
the server or (with the
exception of cookies) to the
web site visitor's computer.
This limitation is not all
bad. Allowing code which a
malicious user could
potentially alter to have
access to the server would be
very bad from a security
standpoint. Similarly, code
which could write data to a
user's computer would expose
the user to potential
security problems.
JavaScript's inability to
store data except with
cookies, however, does render
it unfit for certain types of
programs.
As I
alluded to earlier, if the
user does not have JavaScript
turned on in the browser, the
Javascript programs will not
run.
Different
browsers often produce
different results from the
same Javascript code. It pays
to test your JavaScript
programs in all of the
browsers you plan to support
to make sure that the
programs behave acceptably.
Learning
Javascript
It's easier to
learn JavaScripts if you are
already somewhat knowledgeable in
html. If you are not, however,
you will likely become more so
along the way, as any good book
or tutorial on JavaScript will
show you how it works with with
html, thus teaching you that
language as well.
There are many
good books written about
JavaScript. I've found the
Microsoft Press book JavaScript(TM) Step by Step
by
Steve Suehring particularly
useful.
Online resources for learning
JavaScript abound as well. Some
worth a look include:
Obviously the preceding
examples are only a small subset
of the many JavaScript sites
available. If there is something
in particular that you want to
know about JavaScript, you can
almost certainly find the answer
online with a little patient
searching. Happy learning!
|
