var map = new BMap.Map("allmap"); map.enableScrollWheelZoom(); map.addControl(new BMap.NavigationControl()); var contextMenu = new BMap.ContextMenu();  map.addContextMenu(contextMenu);  var gc = new BMap.Geocoder();  var marker;  function AddMarker(point) {      map.clearOverlays();       marker = new BMap.Marker(point);        map.addOverlay(marker);            marker.enableDragging();  }map.centerAndZoom(new BMap.Point(113.972,23.061213), 15);AddMarker(new BMap.Point(113.972,23.061213));