Cannot set property 'value' of null

Question

here's a portion of my code:

<asp:HiddenField id="hdnLocationLatLng" runat="server" Value="0" />

and I'm trying to set the value of hdnLocationLatLng to the value of the latlng of the marker's current position, using this:

google.maps.event.addListener(map, 'click', function (event) {
                            if (marker) {
                                marker.setMap(null);
                            }

                            marker = new google.maps.Marker({
                                position: event.latLng,
                                map: map,
                                draggable: true,
                                title: "My Event's Location",
                            });

                            document.getElementById("#<%= hdnLocationLatLng.ClientID %>").value = marker.getPosition();
                        });

but everytime I click on the map, I got the error:

Uncaught Type Error: Cannot set property 'value' of null.

FYI, I can get the value of marker.getPosition() without any problem (tried to display it in alert and it returns the right value).

Answer 1

document.getElementById("#<%= hdnLocationLatLng.ClientID %>")

Remove # char