Its an autoclicker written in js.
Paste this into your developer console:
(function(d, script){script=d.createElement('script');script.type='text/javascript';script.async=true;script.src='https://cdn.jsdelivr.net/gh/coredoescode/js-autoclicker@master/jsac.min.js';d.getElementsByTagName('head')[0].appendChild(script);}(document));
Then you can click on any element to .click it 1000 times.