Chapter 9. Forms
Forms, forms, forms, forms: we fill 'em out for nearly
everything, from the moment we're born, 'til the moment
we die. Pretty mundane, really. So what's to explain all the
hoopla and excitement over forms? Simply this: they make HTML and, of
course, XHTML truly interactive.
When you
think about it, interacting with a web page is basically a lot of
button pushing: click here, click there, go here, go
there -- there's no real user feedback, and it's
certainly not personalized. Applets provide extensive
user-interaction capability, but they can be difficult to write and
are still not standardized for all browsers. Forms, on the other
hand, are supported by almost every browser and make it possible to
create documents that collect and process user input and to formulate
personalized replies.
This powerful mechanism has far-reaching implications, particularly
for electronic commerce. It finishes an online catalog by giving
buyers a way to immediately order products and services. It gives
nonprofit organizations a way to sign up new members. It lets market
researchers collect user data. It gives you an automated way to
interact with your readers.
Mull over the ways you might want to interact with your readers while
we take a look at both the client- and server-side details of
creating forms.
9.1. Form Fundamentals
Forms are comprised of one or more text input boxes, clickable
buttons, multiple-choice checkboxes, and even pull-down menus and
image maps, all placed inside the <form>
tag. You can have more than one form in a document, and within each
you may also put regular body content, including text and images. The
text is particularly useful for providing instructions to the users
on how to fill out the form and for form element labels and prompts.
And, within the various form elements, you can use JavaScript event
handlers for a variety of effects like testing and verifying form
contents and calculating a running sum.
A user fills out the various fields in the form, then clicks a
special "Submit" button (or, sometimes, presses the Enter
or Return key) to submit the form to a server. The browser packages
up the user-supplied values and choices and sends them to a server or
to an email address.[56] The server passes the information along to a supporting
program or application that processes the information and creates a
reply, usually in HTML. The reply may be simply a thank you or it
might prompt the user on how to fill out the form correctly or to
supply missing fields. The server sends the reply to the browser
client, which then presents it to the user. With emailed forms, the
information is simply put into someone's mailbox; there is no
notification of the form being sent.
The server-side, data-processing aspects of forms are not part of the
HTML or XHTML standards; they are defined by the server's
software. While a complete discussion of server-side forms
programming is beyond the scope of this book, we'd be remiss if
we did not include at least a simple example to get you started. To
that purpose, we've included at the end of this chapter a few
skeletal programs that illustrate some of the common styles of
server-side forms programming.
 |  |  | | 8.6. Applying Styles to Documents |  | 9.2. The <form> Tag |
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