What do the CloudFlare CAPTCHA and Challenge pages look like for users?

Question

In the CloudFlare Web Application Firewall you are able to block, whitelist, CAPTCHA, or JavaScript Challenge traffic based on IP address, country name, or ASN. The only note provided on the CAPTCHA section is:

If you are unsure whether suspicious web visitor behavior is illegitimate traffic, you can set up a challenge page. This page asks visitors to submit a CAPTCHA successfully to continue their action. If the web visitor fails the challenge, they will be blocked from your website.

What do the CAPTCHA and challenge pages looks like?

Answer 1

Recently CloudFlare added another option to their Firewall section called JavaScript Challenge, which will display a loading page with three animated dots for up to 5 seconds:

It appears to also use cookies to save the results and allow future access without re-testing.