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.
In a default WordPress installation, the robots.txt file does not exist in your web site’s root directory. WordPress dynamically generates robots.txt content for your web site when it receives a request for the robots.txt file. The technique shown in this article will modify the contents of WordPress’ dynamically generated robots.txt contents.