关于百度地图（离线）使用过程报“Cannot read property 'jb' of undefined ”错误的解决办法

<div id="map_canvas" style="width: 99%; height: 720px; margin-left: 0; margin-top: 0"></div>

<script>
       var defaultCursor = null;

       var tileLayer = new BMap.TileLayer();
       tileLayer.getTilesUrl = function (tileCoord, zoom) {
           var x = tileCoord.x;
           var y = tileCoord.y;
           var url = roadmapPath + zoom + '/' + x + '/' + y + format;
           return url;
       }
       var tileMapType = new BMap.MapType('tileMapType', tileLayer, { minZoom: minLevel, maxZoom: maxLevel });
       var map = new BMap.Map('map_canvas', { mapType: tileMapType });

       //初始化鼠标
       defaultCursor = map.getDefaultCursor();
       // 定位到地图中心点
       map.centerAndZoom(new BMap.Point(centX, centY), 12);
       // 添加导航控件
       map.addControl(new BMap.NavigationControl());
       //缩略地图控件
       //map.addControl(new BMap.OverviewMapControl());
       map.addControl(new BMap.OverviewMapControl({ isOpen: true, anchor: BMAP_ANCHOR_BOTTOM_RIGHT }));
       //地图类型控件
       map.addControl(new BMap.MapTypeControl({ mapTypes: [BMAP_NORMAL_MAP, BMAP_SATELLITE_MAP] }));
       // 添加比例尺控件
       map.addControl(new BMap.ScaleControl({ anchor: BMAP_ANCHOR_TOP_LEFT }));
       // 启用滚轮放大缩小
       map.enableScrollWheelZoom();
       map.enableContinuousZoom();
       //启用键盘操作
       map.enableKeyboard();
</script>