这种 js 混肴代码怎么反混肴，!+[]+!![]+[]...

完整的代码是这样的，以前好像有看到过哪里可以发混肴的，一时想不起来了。
(function(){
var a = function() {try{return !!window.addEventListener} catch(e) {return !1} },
b = function(b, c) {a() ? document.addEventListener("DOMContentLoaded", b, c) : document.attachEvent("onreadystatechange", b)};
b(function(){
var a = document.getElementById('cf-content');a.style.display = 'block';
setTimeout(function(){
var s,t,o,p,b,r,e,a,k,i,n,g,f, VTDktxa={"bNdVqScWyCy":+((!+[]+!![]+[])+(!+[]+!![]))};
t = document.createElement('div');
t.innerHTML="<a href='/'>x</a>";
t = t.firstChild.href;r = t.match(/https?:\/\//)[0];
t = t.substr(r.length); t = t.substr(0,t.length-1);
a = document.getElementById('jschl-answer');
f = document.getElementById('challenge-form');
;VTDktxa.bNdVqScWyCy-=+((!+[]+!![]+!![]+[])+(!+[]+!![]));VTDktxa.bNdVqScWyCy+=+((!+[]+!![]+[])+(!+[]+!![]+!![]+!![]));VTDktxa.bNdVqScWyCy+=!+[]+!![]+!![]+!![]+!![]+!![]+!![];VTDktxa.bNdVqScWyCy*=+!![];a.value = parseInt(VTDktxa.bNdVqScWyCy, 10) + t.length; '; 121'
f.submit();
}, 4000);
}, false);
})();