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回复内容： 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这种简单的东西压根起不到加密的效果，骗骗小孩罢了。
原理上无非就是将js代码作为字符串，对这个字符串进行escape一类的混淆，执行时不过unescape再eval一下。
this.eval=function (s) { console.log(s);};
这样不就能得到原来的代码了么：
var fangke_xhead = document.getelementsbytagname('head').item(0);var para = document.getelementbyid(qq_js);var v;var v = para.src;var tmp = v.split(?);var ids = tmp[1];var url = tmp[0].split(count.js);function skip() { if (document.getelementbyid('qqfangke_iframe') == null) { var qqfangke_xurl = 'http://qq-812631263.huantu.net/t-census.php?' + ids; var qqfangke_ref = encodeuricomponent(document.referrer); var qqfangke_page = encodeuricomponent(document.location.href); var qqfangke_url = qqfangke_xurl + '&url=' + url[0] + '&llurl=' + qqfangke_ref + '&thepage=' + qqfangke_page + '&t=' + new date().gettime(); var iframe = document.createelement(iframe); iframe.src = qqfangke_url; iframe.id = qqfangke_iframe; iframe.name = qqfangke_iframe; iframe.style.width = 0px; iframe.style.height = 0px; iframe.scrolling = no; iframe.setattribute('frameborder', '0', 0); document.body.appendchild(iframe) }}skip();
举一隅不以三隅反，则免不了调试代码通宵～
我没有明说的是，它的代码进行了好几次的解码，所以原代码第一次运行时，eval方法截获的字符串仍然是一个eval(substantialcode)形式的字符串，所以需要将其中substantialcode再执行一次，反复此方法，最终eval会截获到原始的代码。
大致这样吧：
var _eval=this.eval;this.eval=function (s) { if (s.indexof(eval)==0) _eval(s); else console.log(s);};