brainf*ck interpreter for Javascript

bf.js

/*@cc_on@*//*@if (@_jscript) var print=function(s){WScript.Echo(s)};@*//*@end@*/
var prompt=function(x,y){return'a'};
var alert = print;

(function(bf){j=s=[];o=p='';b=[m=0];bf=bf.split('');
  for(i in bf)(c=bf[i])=='['?s.push(i):c==']'?j[j[i]=s.pop()]=i:0;
  for(i=0;c=bf[i],i<bf.length;++i)
    c=='>'?b[++m]=b[m]||0:
    c=='<'?--m:c=='+'?++b[m]:
    c=='-'?--b[m]:c=='['?b[m]||(i=j[i]):
    c==']'?b[m]&&(i=j[i]):
    c==','?(b[m]=((p=prompt('>',''))&&p.length)?p.charCodeAt(0):0):
    c=='.'?o+=String.fromCharCode(b[m]):0;
  alert(o)
})('++++++++[>++++++++<-]>+.');
//})((S=(D=document).selection)?D.S.createRange().text:D.getSelection());