Google Maps - directions from users geo-location

Question

I have the following function that checks if the browser supports geo-location and then gets the users geo-location and centres it on the map.

What do I need to add to allow me to give the users direction to a fixed location (this won't change) from the users geo-location?

if (navigator.geolocation)
{
  navigator.geolocation.getCurrentPosition(function(position)
  {                                                              
    var latitude = position.coords.latitude;                    
    var longitude = position.coords.longitude;                 
    var coords = new google.maps.LatLng(latitude, longitude);
    var directionsDisplay;
    var directionsService = new google.maps.DirectionsService();
    var mapOptions = 
    {
      zoom: 15,  
      center: coords, 
      mapTypeControl: true, 
      navigationControlOptions:
      {
        style: google.maps.NavigationControlStyle.SMALL
      },
       mapTypeId: google.maps.MapTypeId.ROADMAP
    };
     map = new google.maps.Map(document.getElementById("mapContainer"), mapOptions);
     var marker = new google.maps.Marker( 
       {
         position: coords, 
         map: map,                 
        });
   });
}
else
{
   alert("Geolocation API is not supported in your browser.");

I've added this function to my code:

  function calcRoute() {
    var start = position;
    var end = "London";
    var request = {
      origin: start,
      destination: end,
      travelMode: google.maps.TravelMode.DRIVING
    };
    directionsService.route(request, function (result, status) {
      if (status == google.maps.DirectionsStatus.OK) {
        directionsDisplay.setDirections(result);
      }
    });
  }

HTML: <div id="mapContainer" onload="calcRoute()"></div>

But it still does not seem to be working.

Answer 1

Got it working with the following code:

if (navigator.geolocation) { //Checks if browser supports geolocation
   navigator.geolocation.getCurrentPosition(function (position) {                                                              //This gets the
     var latitude = position.coords.latitude;                    //users current
     var longitude = position.coords.longitude;                 //location
     var coords = new google.maps.LatLng(latitude, longitude); //Creates variable for map coordinates
     var directionsService = new google.maps.DirectionsService();
     var directionsDisplay = new google.maps.DirectionsRenderer();
     var mapOptions = //Sets map options
     {
       zoom: 15,  //Sets zoom level (0-21)
       center: coords, //zoom in on users location
       mapTypeControl: true, //allows you to select map type eg. map or satellite
       navigationControlOptions:
       {
         style: google.maps.NavigationControlStyle.SMALL //sets map controls size eg. zoom
       },
       mapTypeId: google.maps.MapTypeId.ROADMAP //sets type of map Options:ROADMAP, SATELLITE, HYBRID, TERRIAN
     };
     map = new google.maps.Map( /*creates Map variable*/ document.getElementById("map"), mapOptions /*Creates a new map using the passed optional parameters in the mapOptions parameter.*/);
     directionsDisplay.setMap(map);
     directionsDisplay.setPanel(document.getElementById('panel'));
     var request = {
       origin: coords,
       destination: 'BT42 1FL',
       travelMode: google.maps.DirectionsTravelMode.DRIVING
     };

     directionsService.route(request, function (response, status) {
       if (status == google.maps.DirectionsStatus.OK) {
         directionsDisplay.setDirections(response);
       }
     });
   });
 }