Function getMaplibreSupportedJMapLayerIdBefore

getMaplibreSupportedJMapLayerIdBefore(layerId): JId | undefined
JMap.Map.getMaplibreSupportedJMapLayerIdBefore

Returns the Map JS library supported JMap layer id that is ordered before the JMap layer id provided in argument.
Parameters
- layerId: JId
  The JMap layer id
Returns JId | undefined
the JMap layer id, or undefined if no layer before
Throws
Error if layer is not found

Example
```
// Returns the layer id that is located before layer id=4
JMap.Map.getMaplibreSupportedJMapLayerIdBefore(4)
```