JavaScript Examples Bible - UserWorks Technologies

Text-Related
Form Objects
(Chapter 25)
When your page needs input from visitors beyond
“yes” or “no” answers, text fields are the interface
elements that provide the blank spaces. Whether you specify
the one-line INPUT element or the multi-line TEXTAREA element,
this is where visitors can not only express themselves,
but also enter information in formats that might cause your
carefully constructed back-end database to go haywire. More
often than not, it is the text box that benefits most from clientside
form validation.
Despite the fact that the primary user action in a text box
is typing, keyboard events became available to scripters only
starting with the version 4 browsers from both Microsoft and
Netscape. But they arrived fully formed, with a suite of events
for the downstroke, upstroke, and complete press-and-release
action of typing a character. From there, the event object
takes over to help scripts uncover the character code and
whether the user held down any modifier keys while typing
the character. You can find examples of this kind of event handling
in the examples for Chapters 1 and 13 of this book.
Text boxes are not always as scriptable as you might like
them to be. Modern browsers can apply style sheets to adjust
font characteristics of the complete text box, but you cannot,
say, set some of the words inside a text box to bold. Even
something as common (in other programs) as having the text
insertion pointer automatically plant itself at the end of existing
text is possible so far only in IE4+/Windows via the
TEXTAREA’s createTextRange() method and associated
TextRange object methods (see TextRange object examples
in Chapter 5 of this book). The moral of the story is to keep
your expectations for the powers of text fields at moderate
levels.
9
C H A P T E R
✦ ✦ ✦ ✦
In This Chapter
Capturing and
modifying text field
contents
Triggering action and
entering text
Giving focus to a text
field and selecting its
contents
✦ ✦ ✦ ✦