You can use jQuery to validate form input data before form submission. Disabling the form inputs during validation and submission seems like a good way to prevent changes to form inputs by the user before the form is processed. But subtle problems can happen if you use the disabled attribute to do this.
Google documents methods to opt-out a user from Google Analytics and tracking on your web site. However, they do not show you how implement this only for users that have the Do-Not-Track or Global Privacy Control settings enabled in their web browser. This article will provide two examples that perform user opt-out on Google Analytics. The techniques shown here could be applied to other analytics and tracking code as well.