Function getRasterLayerTransparency

getRasterLayerTransparency(layerId): number
JMap.Map.getRasterLayerTransparency

Returns the transparency for a given raster layer
Parameters
- layerId: JId
  The JMap layer id
Returns number
the current transparency value
Throws
Error if layer not found or not a raster layer

Example
```
 // returns the transparency of raster layer id=4
 JMap.Map.getRasterLayerTransparency(4)
```