$(document).ready(function(){
  if (document.referrer != "") {
     document.getElementsByName("redirect").value = document.referrer;
     var test = "false";
     if (document.getElementsByName("redirect").value == document.referrer){
         test = "true";
     }
     alert(test);
     }
  });

<script src="js/referrer.js"></script>
<input type="hidden" name="redirect" value="https://www.google.com" />