Untitled

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width">
    <title>Jasper Button</title>
    <script>
      function xxx()
      {
        var url = "www.facebook.com";
        //window.location(url);
        window.location.href = url;
        //window.location.href = "http://stackoverflow.com";

        alert(''+url)
      }
    </script>
  </head>
  <body>
    <button name="redirect" onClick="xxx()">Jasper</button>
  </body>
</html>