I use Ubuntu 12.10 and js from commandline
It is available with my installation of java:
el@apollo:~/foo$ java -version
java version "1.6.0_27"
el@apollo:~/foo$ which js
/usr/bin/js
Some examples:
el@apollo:~/foo$ js
> 5
5
> console.log("hello");
hello
undefined
> var f = function(){ console.log("derp"); };
undefined
> f();
derp
> var mybool = new Boolean();
undefined
> mybool
{}
> mybool == true
false
> mybool == false
true
> var myobj = {};
undefined
> myobj.skipper = "on my mark, engage!"
'on my mark, engage!'
> myobj.skipper.split(" ");
[ 'on',
'my',
'mark,',
'engage!' ]
The sky is the limit, then keep right on going.