Cant show direction google maps

I want show direction with google maps API from variable. If langitude and longitude manually input can show the direction but if get from variable the direction not show.

<script>
  var jos = -6.578583; //langitude
  var josu = 106.807714; //longitude
  function initMap() {
    var directionsDisplay = new google.maps.DirectionsRenderer;
    var directionsService = new google.maps.DirectionsService;
    var map = new google.maps.Map(document.getElementById('map'), {
      zoom: 14,
      center: {lat: -6.578583, lng: 106.807714}
    });
    directionsDisplay.setMap(map);

    calculateAndDisplayRoute(directionsService, directionsDisplay);

  }

  function calculateAndDisplayRoute(directionsService, directionsDisplay) {
    var selectedMode = document.getElementById('mode').value;
    directionsService.route({
      origin: {lat: jos, lng: josu}, // **THE ISSUE** 
      destination: {lat: -6.578583, lng: 106.807714}, 
      travelMode: google.maps.TravelMode[selectedMode]
    }, function(response, status) {
      if (status == 'OK') {
        directionsDisplay.setDirections(response);
      } else {
        window.alert('Directions request failed due to ' + status);
      }
    });
  }
</script>