You might see an Anubis anti-bot Proof-of-Work check to keep the site safe from...

https://iris-wiki.win/index.php/Why_does_Anubis_prefer_JavaScript_instead_of_a_server-side_check%3F

You might see an Anubis anti-bot Proof-of-Work check to keep the site safe from automated traffic. It runs a simple test in your browser using JavaScript. If JavaScript doesn’t load, the check can’t finish