Do you really have to run JavaScript?
For example, there is a script which logs on a forum, reads latest messages and decides which ones are posted by (just plain stupid) spam robots. Nearly half of the forum administration is javascript-driven, but all of it can be avoided by some simple things like:

$ssid=$1 if $bot->content =~ m/name="ssid" value="([^"]+)"/;
$bot->post($posturl,{ act => 2, reason => "spambot", ever => 1, a => $
+a, s => $s, t => $t, ssid => $ssid});
<...>
($key) = ($bot->content =~ /'(-8-0-[a-zA-Z0-9]+)'/)
<...>
$bot->content =~ /display='none'/ ? print " Removed\n" : warn "Failed 
+to remove the message, remove url $victim\n";
[download]

You just need to read the javascript, understand it and do similar things yourself.