Get POV heading for StreetViewPanorama

example.js

function initialize() {
  // initialize the geocoder API functions. We need this to convert the address to a geolocation (GPS coordinates)
  var geocoder =  new google.maps.Geocoder();
  // then we call the geocode function with the address we want to use as parameter
  geocoder.geocode( { 'address': '20 River Terrace, New York, NY, United States' }, function(results, status) {
    // set the lookTo var to contain the coordinates of the address entered above
    var lookTo = results[0].geometry.location;
    // if the address is found and the geocoder function returned valid coordinates
    if (status == google.maps.GeocoderStatus.OK) {
      // set the options for the panorama view
      var panoOptions = {
        position: lookTo,
        panControl: false,
        addressControl: false,
        linksControl: false,
        zoomControlOptions: false
      };
      // initialize a new panorama API object and point to the element with ID streetview as container
      var pano = new  google.maps.StreetViewPanorama(document.getElementById('streetview'),panoOptions);
      // initialize a new streetviewService object
      var service = new google.maps.StreetViewService;
      // call the "getPanoramaByLocation" function of the Streetview Services to return the closest streetview position for the entered coordinates
      service.getPanoramaByLocation(pano.getPosition(), 50, function(panoData) {
        // if the function returned a result
        if (panoData != null) {
          // the GPS coordinates of the streetview camera position
          var panoCenter = panoData.location.latLng;
          // this is where the magic happens!
          // the "computeHeading" function calculates the heading with the two GPS coordinates entered as parameters
          var heading = google.maps.geometry.spherical.computeHeading(panoCenter, lookTo);
          // now we know the heading (camera direction, elevation, zoom, etc) set this as parameters to the panorama object
          var pov = pano.getPov();
          pov.heading = heading;
          pano.setPov(pov);
          // set a marker on the location we are looking at, to verify the calculations were correct
          var marker = new google.maps.Marker({
            map: pano,
            position: lookTo
          });
        } else {
          // no streetview found :(
          alert('not found'); 
        }
      });
    } else {
      // there were no coordinates found for the address entered (or the address was not found)
      alert('Could not find your address :(');
    }
  }); 
}