Validation of date entered in text box???

Howdy folks,
New to ASP.nET development. I am using vs 2008 (asp.net 3.5). I used a ajax calendar control  (CalendarExtender1) on the text box.
Once the user selects a date using the calendar control, when he clicks on "go" button, I want to validate the user input and throw message. I don't want to validate the user input on the server. Is there a way to check on the client side to see if the user entered a date (in the formate mm/dd/yyyy)?
thanks
nath
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