Pure JavaScript/jQuery/HTML captcha

Question

can somebody sent me a link, or to provide me an example with pure Javascript/jQuery captcha. Because I can see a lots of examples with PHP/C# ... back end. But I need just

Answer 1

Check out: http://www.google.com/recaptcha/intro/

Demo here: http://www.google.com/recaptcha/api2/demo OR http://www.finalwebsites.com/demos/custom-captcha-image-script/

===========================IN SHORT====================

Add the code snippet to the page for the captcha to occur:

whenever user complete the challenge, a textArea named g-recaptcha-response with value is populated, you will collect that value and send below request to validate it: https://www.google.com/recaptcha/api/siteverify?secret=YOUR_KEY_2&response=TOKEN&remoteip=IPADDRESS

Getting the IP using js may be troublesome: http://www.ipify.org/