In the context of the question, that is not relevant. reCAPTCHA requires JavaScript as well. The question is about an alternative to reCAPTCHA. Both methods use JavaScript.
I do understand where you are coming from though. And I also think this alternative is better in this regard. reCAPTCHA loads JavaScript from a third-party domain. With JavaScript spamfilters you are loading them from the first-party domain.
reCaptcha has a noscript alternative with iframes and checkboxes. Once completed you have to manually copy an authorisation string to a field and submit it.
I do understand where you are coming from though. And I also think this alternative is better in this regard. reCAPTCHA loads JavaScript from a third-party domain. With JavaScript spamfilters you are loading them from the first-party domain.