问Google地图绘制路径在某一时刻仍然有效

EN

function renderDirections(result) {

  var directionDisplay = new google.maps.DirectionsRenderer();
  directionDisplay.setMap(map);
  directionDisplay.setDirections(result);
  directionDisplay.setOptions({suppressMarkers: true});
}

for(var i=0; i < array.length; i++){

                    var marker = new google.maps.Marker({
                    position: new google.maps.LatLng(array[i].lat, array[i].lng),
                    map: map                                 
                    });

                    var directionsService = new google.maps.DirectionsService();
                    directionsService.route({
                    origin:  new google.maps.LatLng(array[i].lat, array[i].lng),
                    destination:  new google.maps.LatLng(array[i+1].lat, array[i+1].lng),
                    unitSystem: google.maps.UnitSystem.IMPERIAL,
                    travelMode: google.maps.DirectionsTravelMode.DRIVING
                    },
                    function(result){
                      renderDirections(result);
                    });
                }