to display the java console:

in the Main menu (nothing else opened)
GO——>applications—->utilities—->java J2SE, java preferences
advanced button
settings, java console
show console radio button!

to display the jscript output window:

in terminal window:
defaults write com.apple.Safari IncludeDebugMenu 1 ;

http://nosheep.net/story/secret-to-debugging-javascript-in-safari/

then in your js do:

window.console.log(“hello world”);

debug options appears FAR RIGHT SIDE of safari window, look for Show Javascript Console about two/thirds of the way down

(this option is also available in firebug)