Mal/FakeAvJs-A is a malicious script, usually found in a page pretending to relate to anti-virus software.
The script is typically used on websites that simulate the behavior of security or anti-virus scanners. The websites often claim that the user viewing the site is infected with one or more viruses and attempt to either install fake security software or persuade the user to buy the fake software.
Various social engineering lures can be used to entice the user to visit the malicious site. One example of this scam, using security rumors to draw users to the site, is described on
Graham Cluley's blog.