↑
Main Page

Forms and Data Integrity

Form elements were created to address the need for the user to send data back to the server. The

answer they provided came in the form (no pun intended) of Web forms, using the HTML

<form/>

, and

elements. Using these elements, browsers can render

text boxes, combo boxes, and other user input controls to allow communication from the client to

the server.

Although the Web has developed at a rapid pace, Web forms have remained virtually unchanged.

Although a new standard called XForms looms on the horizon, no browser has made a move to

adopt it natively, and so Web forms today rely on JavaScript to augment the built-in behavior.

In this chapter, you learn how to use JavaScript to extend the behavior and usability of common

Web forms to include the functionality that today’s users expect.

Form Basics

An HTML form is defined by using the

<form/>

element, which has several attributes:

method

— Indicates whether the browser should sent a GET request or a POST request

action

— Indicates the URL to which the form should be submitted

enctype

— The way the data should be encoded when sent to the server. The default is

application/x-www-url-encoded

, but it may be set to

multipart/form

data

if the

form is uploading a file.

— Lists the mime types the server will handle correctly when a file is uploaded

accept-charset

— Lists the character encodings that are accepted by the server when

data is submitted

14_579088 ch11.qxd 3/28/05 11:40 AM Page 335