What's the best way to make sure the users only enter numbers in the web page textboxes? My options I think are:

1. Running a jscript to check each field just prior to form submission and prompt the user to enter only numbers.
2. When posting entered data, call a function to convert all values to numeric.

I have a form with 50 textboxes that should only have numbers when it's posted and unsure from standpoint of accuracy and performance which method is best.