Function isAllLayerParentsVisible

isAllLayerParentsVisible(layerId): boolean
JMap.Layer.isAllLayerParentsVisible

Returns true if all parents of the element have the visibility property equals to true.

If element has no parent it returns true.
Parameters
- layerId: JId
  The JMap layer id
Returns boolean
Throws
Error if no layer found for the id

Example
```
// returns true if all parents of layer id=3 have the property visible set to true
JMap.Layer.isAllLayerParentsVisible(3)
```