Function isActive

isActive(layerId): boolean
JMap.Layer.DynamicFilter.isActive

Returns true if the layer has a dynamic filter, and its filter is active.

Doesn't throw if the given layer doesn't support dynamic filter.
Parameters
- layerId: JId
  The JMap layer id
Returns boolean
Example
```
// returns true if layer has dynamic filter, and filter is active
JMap.Layer.DynamicFilter.isActive(5)
```