Here’s a nice way of enabling a button on a form IFF the Accept T&C checkbox has been clicked

Knockout script

So we have a simple acceptTerms variable that is observable

Markup

In the markup above you can see that the input of id “agree” has bound it’s checked state to the observable, we also see that the submit button has bound it’s enable state.

Pretty simple solution client side solution if you’re already using knockout in your application.