Function subFormDialogOpened

subFormDialogOpened(listenerId, fn): void
JMap.Event.Form.on.subFormDialogOpened

This event is triggered each time a sub form dialog is opened.
Parameters
- listenerId: string
  Your listener id (must be unique)
- fn: ((params) => void)
  Your listener function
  - - (params): void
    - Parameters
      params: JFormLayerDialogOpenEventParams
      Returns void
Returns void
Example
```
// log a message in the console once a sub form dialog has been opened
JMap.Event.Form.on.subFormDialogOpened(
  "custom-sub-form-dialog-opened",
  params => console.info(`Sub form dialog opened for layer id="${params.layerId}"`, params.subForm)
)
```