I'm looking for an efficient but well written script for error-checking use on my shopping cart page. On my shopping cart form, where people enter the quantity they want to buy, I need the form to limit their input to numbers only and quantity limited to 99. For example, if someone enters "4A" I want the quantity to show only 4; another example, if someone enters 68, it will show 68, but if they enter 684 it will drop the first digit entered and only display 84.
I'm not a programmer, so please keep my install instructions simple.
Thank you for your help.