The Java and Javascript languages execute programs or applets in
the browser. However, since not all browsers will necessarily have
this functionality, it's doubtful whether a Web Commerce system
should utilise them -- certainly they shouldn't
depend on them. Nevertheless, they can be
useful:
Interactivity can, if well done, make a page more attractive to
some users.
A Java applet can communicate with the server using other
protocols than HTTP. This opens up a range of possibilties.
An applet (or a Javascript program) can be used to check FORM
information for consistency and completeness before allowing it to
be sent to the server. For example:
check if all important TEXT boxes have been filled in.
perform limited syntax check of email addresses, phone numbers,
addresses, etc.
check credit card numbers for correctness (prefix and
checksum)
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