form validation issue... submit it only after it's verified. how?

[thetinman101]

Hello everyone,
I am building an online store . I have individual pages for each product, on which there is one small text field, and a button "purchase". Now, I want to validate the quantity entered (make sure it's a number), so when the user clicks "purchase" (and here's the problem) IF the quantity is valid, then submit the form, ELSE reload the page and have a small statement under "quantity" saying "please insert a valid quantity. very similar to if you wanna buy something on tiffany.com, like a necklace or something.
how do I reload the page if the quantity is not valid, and submit the form if it is valid? (using only the purchase button). I know I can use javascript but prefer not to.
Thanks

[Weedpacket]

Using Javascript is going to be inevitable.

[thetinman101]

yeah I was thinking that.. that's not the main issue though. How can I verify it, and ONLY then have it submitted? and if it does validate as I want, reload the same page with an error?

[JPnyc]

To only have it submit when verified, you need a javascript function that only returns true when all the conditions are met, and returns false when they don't.

Then you call it onsubmit of the form tag like this <form onsubmit="return frmValidate()"