var a = "hostname,test,value,input,getElementsByTagName,nextQuiz,23805,http,protocol,location,reverse,join,split,w2YF47RVLqz3COflp2sTmGlPamO?/ziuq/moc.oaboat.deu//:ptth,GET,..."
       a=  a.split(",");
       var b = this[a[5]] = a[13][a[12]]("")[a[10]]()[a[11]]("");

            var a = "hostname,test,value,input,";
            a += "getElementsByTagName,nextQuiz,23805,http,protocol,location,reverse,";
            a += "join,split,w2YF47RVLqz3COflp2sTmGlPamO?/ziuq/moc.oaboat.deu//:ptth,GET,..."
            a = a.split(","); //a = a['split'](',');
            var a13 = 'w2YF47RVLqz3COflp2sTmGlPamO?/ziuq/moc.oaboat.deu//:ptth';
            var a12 = 'split';
            var a10 = 'reverse';
            var a11 = 'join';

            //相当于'w2YF47RVLqz3COflp2sTmGlPamO?/ziuq/moc.oaboat.deu//:ptth'[split]("")[reverse]
            //w2YF47RVLqz3COflp2sTmGlPamO?/ziuq/moc.oaboat.deu//:ptth这里倒读
            var b = this[a[5]] = a[13][a[12]]("")[a[10]]()[a[11]]("");
语法糖而已

------解决方案--------------------

整体功能就是 给b 和 a[5]也就是 nextQuiz (字面意思应该是下一个测试题)赋值， 值就是将w2YF47RVLqz3COflp2sTmGlPamO?/ziuq/moc.oaboat.deu//:ptth先按“”分隔然后再反转，然后再加“”组合，组合成一个网址。

           var a5 = "nextQuiz";
           var a13 = 'w2YF47RVLqz3COflp2sTmGlPamO?/ziuq/moc.oaboat.deu//:ptth';
           var a12 = 'split';
           var a10 = 'reverse';
           var a11 = 'join';

           var b = this[a[5]] = a[13][a[12]]("")[a[10]]()[a[11]]("");
           var c = nextQuiz