帮我看看这段加密的文本如何解密

Question

document.write(unescape("%3Cscript%3E%0D%0A%3C%21--%0D%0Adocument.write%28unescape%28%22%253Cscript%253E%250D%250A%253C%2521--%250D%250Adocument.write%2528unescape%2528%2522%25253Cscript%252520language%25253D%252522JavaScript%252522%252520type%25253D%252522text/JavaScript%252522%25253E%25250D%25250A//%252520JavaScript%252520Document%25250D%25250A//%252520%2525u7981%2525u6B62ASP%2525u540E%2525u7F00%25250D%25250Avar%252520url%25253Dwindow.location.href%25253B%252520%252520%25250D%25250Avar%252520a%25253Durl.toUpperCase%252528%252529.indexOf%252528%252522ASP%252522%252529%25253B%25250D%25250Aif%252520%252528a%252520%252521%25253D-1%252520%252520%252529%25250D%25250A%25257B%25250D%25250Awindow.top.location.replace%252520%252528%252522err.html%252522%252529%25250D%25250A%25257D%25250D%25250Aelse%252520%25250D%25250A%25257B%25250D%25250A%25250D%25250A%25257D%25250D%25250A%25253C/SCRIPT%25253E%2522%2529%2529%253B%250D%250A//--%253E%250D%250A%253C/script%253E%22%29%29%3B%0D%0A//--%3E%0D%0A%3C/script%3E"));

Answer 1

解密后的代码：
<script language="JavaScript" type="text/JavaScript">
// JavaScript Document
// 禁止ASP后缀
var url=window.location.href;  
var a=url.toUpperCase().indexOf("ASP");
if (a !=-1  )
{
window.top.location.replace ("err.html")
}
else 
{}
</SCRIPT>

Answer 2

这应该是escape编码之后的代码吧，然后用unescape解码后输出了