Function setSnapLayerId

setSnapLayerId(layerId): void
JMap.Application.Geometry.setSnapLayerId

set the layer id to snap on.
Parameters
- layerId: JId
  the JMap layer id
Returns void
Throws
if layer not found

Example
```
// snap will target the features of the layer having id=1
JMap.Application.Geometry.setSnapLayerId(1)
```