Who are you, before we let you in?

The Source Code:

<html><head>
<p><script>
function SpecialPermission() {
varWhoAreYou = prompt("Who are you?","");
if (varWhoAreYou != null) {
       if (varWhoAreYou == "") {
              alert("You left it blank!");
       } else {
              if (varWhoAreYou == "hal") {
                     location.href="http://www.apache.org";
              } else {
                     location.href="http://www.microsoft.com/iis";
              }
       }
}
}
</script>
</head>
<body onLoad="SpecialPermission()">
<h1>Who are you, before we let you in?</h1>