Function isAvailable

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

Returns true if the layer support dynamic filter.

For example raster layers don't support dynamic filter.
Parameters
- layerId: JId
  The JMap layer id
Returns boolean
Example
```
// returns true if layer id=5 support dynamic filter, else false
JMap.Layer.DynamicFilter.isAvailable(5)
```