Reverse java script

<script type="text/javascript">
function usercheck() {
input_user=document.fx.user.value;
pass_val="\"eHgMYUn_MWW[SLZ!kKOiM\\SX[Uif'GcaO]YU`eWPJIv|g`YTVTlrUPQT`R_T MgIO~pcM[QHaQVrYI^u'f,ueHgMYU,";
aNum=0;
ax2=1;
for(var i=0;i<input_user.length;i++){
cx=input_user.substring(i,i+1);
aNum=aNum+input_user.charCodeAt(i);
ax2=(ax2*input_user.charCodeAt(i))%65537;
}
if (aNum==1286&&ax2==16628) {
p_val="";
for(var i=0;i<pass_val.length;i++)
{ hehe=input_user.charCodeAt(i%input_user.length)-32;
heh2=pass_val.charCodeAt(i)-32;
alert (heh2);
hehe=heh2-hehe+96;
if(hehe>95) hehe=hehe-96;
hehe=hehe+32;
p_val=p_val+String.fromCharCode(hehe);
}
msgWindow=window.open("","displayWindow","menubar=yes");
msgWindow.document.writeln("<html\><body onload=blah()\>Access Denied");
msgWindow.document.writeln("<font color=white\>hehe");
msgWindow.document.writeln(p_val);
msgWindow.document.writeln("</font\></body\></html\>");
msgWindow.document.close();
}
else {
alert("Go home!");
window.location.href="http://www.disney.com";
}
}
</script>