FORM fields checking

I have a simple form with several checkboxes. Now I need to prevent users to 开发者_如何学Cproceed with this form if more then 3 checkboxes are selected. How should this be done?

Prevent the user from proceeding in what fashion?

On general way would be to simply keep track of the number of check boxes checked within your checkbox check methods. In each check method, check your checkbox count variable and you can proceed from there how you want to prevent the user from interacting with your form.