gistfile1.js

function getElevation(event) {
        var elevator;
        elevator = new google.maps.ElevationService();

        var locations = [];
        // Retrieve the clicked location and push it on the array
        var clickedLocation = event.latLng;
        locations.push(clickedLocation);

        // Create a LocationElevationRequest object using the array's one value
        var positionalRequest = {
          'locations': locations
        }

        // Initiate the location request
        elevator.getElevationForLocations(positionalRequest, function(results, status) {
          if (status == google.maps.ElevationStatus.OK) {

            // Retrieve the first result
            if (results[0]) {
              // Open an info window indicating the elevation at the clicked position
              var altitude = '' + results[0].elevation + ''
              alert(altitude);
            } else {
              alert('No results found');
             }
          } else {
             alert('Elevation service failed due to: ' + status);
          }
        });
  }