Before getting angry on me, please think a bit. Actually such stuff exists in web you visit. They actually do things under your name and different from me, they do not tell you about it. Also I do not let your browser send this data back to me while techincally this is not a problem at all. This is just a demo here, not real attack. Yes, portscan is real.
Credits to SPI Dynamics and http://www.gnucitizen.org/projects/javascript-port-scanner/