您可以参考这两篇CSDN博文来实现js关联查询的操作
SuperMap iClient for JavaScript 之连接查询-JoinItem:https://blog.csdn.net/supermapsupport/article/details/49998205
iClient客户端之关联查询-LinkItem:https://blog.csdn.net/supermapsupport/article/details/52572791