Function activate

activate(listenerId): void
JMap.Event.Layer.activate

Activate the listener.

If the listener is already active, do nothing.

If the listener is inactive, it will be reactivated and will be called again ... when en event is emitted.
Parameters
- listenerId: string
  The listener id
Returns void
Example
```
// activate the listener "my-layer-listener"
JMap.Event.Layer.activate("my-layer-listener")
```