mmmm there are lots wierdos out there - client side validation is the most efficient, if are concerened about this minority you can do it on the server side. IMO - how many people fit into this category and do we need thier business.
;;;Also how about other checking for others such as date/time, number?
To check for an integer:
alert("not a valid number
Dates : dont let them enter them manualy - give them a date picker then just check for ""
If its turned on it will work - all my form validation is done with JS
Wind is your friend