Hover over or click features on the map.
This example shows how to use the 'featureclick', 'nofeatureclick', 'featureover' and 'featureout' events to make features interactive. Look at the feature-events.js source code to see how this is done.
Note that these events can be registered both on the map and on individual layers. If many layers need to be observed, it is recommended to register listeners once on the map for performance reasons.