你好,获取图层还可以根据图层名,帮助文档链接: http://support.supermap.com.cn:8090/iserver/iClient/forJavaScript/apidoc/files/SuperMap/Map-js.html#SuperMap.Map.getLayersByName
图层是否可见查看图层visibility属性 http://support.supermap.com.cn:8090/iserver/iClient/forJavaScript/apidoc/files/SuperMap/Layer-js.html#SuperMap.Layer.visibility