How to disable the submit button until recaptcha2 is verified?

[Technologx]

I have a url shortening site and I want to disable the submit button until the recaptcha2 is verified how do I go about doing that?

Here’s the link to the code: http://bit.ly/1Rs1N8m

This is the shortening form code for a faster look:
[php]

Enter web address (URL) here:

Custom alias (optional):
<?php echo SITE_URL ?>/
May contain letters, numbers, dashes and underscores.

[/php]

My database is getting full of spam urls and I want to add recaptcha2 and have it working to stop these spam bots

[astonecipher]

Did you fix the issue of it bypassing the captcha in your last topic?

[Technologx]

A friend of mine helped me fix the issue lastnight