refresh_app.html

    <script type="text/javascript">
    (function(){

        var timestamp = 0;
        var client = new XMLHttpRequest();
        var interval = setInterval(setRefresh, 500);
        console.log('setting refresh interval id...', interval);

        function getTimestamp(callback) {
          client.open("HEAD", "http://localhost:8001/archer/dist/app.js", true);
          client.send();
          client.onreadystatechange = function() {
            if(this.readyState == this.HEADERS_RECEIVED) {
              var ts = Date.parse(this.getResponseHeader('Last-Modified'));
              callback(ts, timestamp);
            }
          }
        }

        function setRefresh() {
          getTimestamp(function(newts, ts) {

            if(ts === 0) {
              timestamp = newts;
            } else if(newts > ts) {
              console.log('refreshing page...');
              clearInterval(interval);
              window.location.reload(false);
            }

           });
        }

    })();
    </script>