查找地图上的图层，要素：

  window.MapLeaflet.eachLayer(function (layer) {
        if (layer !== window.MapLeaflet) {
             console.log("layer instanceof L.Polyline", layer instanceof L.Polyline)
             //   L.Marker,L.Polyline, L.Polygon||L.Rectangle,L.CircleMarker, L.Circle
             if (layer instanceof L.Polyline) {
                  window.MapLeaflet.removeLayer(layer);
             }
             if (layer instanceof L.CircleMarker) {
                  window.MapLeaflet.removeLayer(layer);
             }
        }
 })

判断类型： 

L.Marker,L.Polyline, L.Polygon||L.Rectangle,L.CircleMarker, L.Circle

判断方法：

layer instanceof L.Polyline

输出：