Prentice Hall and Sun Microsystems. Personal use only; do not redistribute.

406

Chapter 16 Using HTML Forms

Check boxes 

HTML Element:

(No End Tag)

Attributes:

NAME

 (required), 

VALUE

, 

CHECKED

, 

ONCLICK

, 

ONFOCUS

, 

ONBLUR

This input element creates a check box whose name/value pair is transmitted

only if the check box is checked when the form is submitted. For instance,

the following code results in the check box shown in Figure 16 14.

Check here if you do not want to 

get our email newsletter

Figure 16 14An HTML check box.

Note that the descriptive text associated with the check box is normal

HTML, and care should be taken to guarantee that it appears next to the

check box. Thus, the 

 in the preceding example ensures that the check

box isn't part of the previous paragraph.

Core Approach

Paragraphs inside a 

FORM

 are filled and wrapped just like regular 

paragraphs. So, be sure to insert explicit HTML markup to keep input 

elements with the text that describes them.

NAME

This attribute supplies the name that is sent to the server. It is required 

for standard HTML check boxes but optional when used with JavaScript.

VALUE

The 

VALUE

 attribute is optional and defaults to 

on

. Recall that the name 

and value are only sent to the server if the check box is checked when 

the form is submitted. For instance, in the preceding example, 

noEmail=on

 would be added to the data string since the box is checked, 

but nothing would be added if the box was unchecked. As a result, serv 

lets or CGI programs often check only for the existence of the check 

box name, ignoring its value. 

Second edition of this book: www.coreservlets.com; Sequel: www.moreservlets.com.

Servlet and JSP training courses by book's author: courses.coreservlets.com.