So You Think You're a JavaScript Whiz?

Try this mind-bender!  What does this JavaScript expression do, if executed in a browser?

($=[$=[]][(__=!$+$)[_=-~-~-~$]+({}+$)[_/_]+($$=($_=!''+$)[_/_]+$_[+$])])()[__[_/_]+__[_+~$]+$_[_]+$$](_/_)

The answer can be found here, once you give up trying to figure it out...