This code is broken. See http://www.jsfuck.com/ instead.
Original conversation is from http://sla.ckers.org/forum/read.php?24,33349.

JSF*ck demo

encode JavaScript with only 6 letters - []()!+

Enter any JavaScript source:

Target:

[ eval ] [ Permalink ]

Thanks : Kenji Aiko