Function layersChange

layersChange(listenerId, fn): void
JMap.Event.Layer.on.layersChange

This event is triggered when a new project has been loaded, and when its layers have been loaded too.

If the project has been unloaded, this event is triggered but the provided layerTree is an empty array (in JMap a project has at least one layer).
Parameters
- listenerId: string
  Your listener id (must be unique for all layer events)
- fn: ((params) => void)
  Your listener function
  - - (params): void
    - Parameters
      params: JLayerEventChangeParams
      Returns void
Returns void
Example
```
// Each time a new project is loaded and its layer have also been loaded,
// this method is processed.
JMap.Event.Layer.on.layersChange(
   "custom-layers-change",
   params => {
     console.log("This is the new project layer three", params.layerTree)
   }
)
```