> For the complete documentation index, see [llms.txt](https://developers.felt.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developers.felt.com/js-sdk/events-reference.md).

# Events reference

Every listener on the Felt controller follows the same pattern: you pass a `handler` (and sometimes an `options` object scoping the listener to a specific entity), and the call returns an unsubscribe function.

```typescript
const unsubscribe = felt.onLayerChange({
  options: { id: "layer-1" },
  handler: ({ layer }) => console.log(layer.bounds),
});

// ...later, when you no longer need the listener
unsubscribe();
```

Always call the unsubscribe function when your UI unmounts or the listener is no longer needed.

## Viewport and map state

| Listener            | Scoping options | Handler receives                                                                                             |
| ------------------- | --------------- | ------------------------------------------------------------------------------------------------------------ |
| `onViewportMove`    | —               | `ViewportState` — fires continuously during movement, including during animations and inertia.               |
| `onViewportMoveEnd` | —               | `ViewportState` — fires once when dragging, zooming, animations, and inertia have finished.                  |
| `onMapIdle`         | —               | Nothing. Fires when the map is fully idle: no transitions, no interaction, all tiles loaded, fades complete. |
| `onBasemapChange`   | —               | `Basemap` — the new basemap.                                                                                 |

## Annotations (elements)

| Listener               | Scoping options | Handler receives                                                                                                                                                          |
| ---------------------- | --------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `onElementCreate`      | —               | `{ element: Element \| null, isBeingCreated: boolean }` — fires repeatedly while the user draws (`isBeingCreated: true`), then a final time with `isBeingCreated: false`. |
| `onElementCreateEnd`   | —               | `{ element: Element }` — fires once, when creation is finished.                                                                                                           |
| `onElementChange`      | `{ id }`        | `{ element: Element \| null, isBeingCreated: boolean }` — `element` is `null` if it was removed.                                                                          |
| `onElementDelete`      | `{ id }`        | Nothing.                                                                                                                                                                  |
| `onElementGroupChange` | `{ id }`        | `{ elementGroup: ElementGroup \| null }`                                                                                                                                  |

## Layers and legends

| Listener                  | Scoping options   | Handler receives                                                                                                                                         |
| ------------------------- | ----------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `onLayerChange`           | `{ id }`          | `{ layer: Layer \| null }`                                                                                                                               |
| `onLayerGroupChange`      | `{ id }`          | `{ layerGroup: LayerGroup \| null }`                                                                                                                     |
| `onLegendItemChange`      | `{ id, layerId }` | `{ legendItem: LegendItem \| null }`                                                                                                                     |
| `onLayerFiltersChange`    | `{ layerId }`     | `LayerFilters` — the bare filters object (`{ style, components, ephemeral, combined }`), with no wrapper. See [Layer filters](/js-sdk/layer-filters.md). |
| `onLayerBoundariesChange` | `{ layerId }`     | `LayerBoundaries \| null`                                                                                                                                |

## Pointer and selection

| Listener            | Scoping options | Handler receives                                                                                                                                             |
| ------------------- | --------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `onPointerClick`    | —               | `MapInteractionEvent` — `{ coordinate, point, features, rasterValues }`. `features` and `rasterValues` are arrays (empty when nothing is under the pointer). |
| `onPointerMove`     | —               | `MapInteractionEvent`                                                                                                                                        |
| `onSelectionChange` | —               | `{ selection: EntityNode[] }` — see [Working with selection](/js-sdk/working-with-selection.md).                                                             |

## Tools

| Listener               | Scoping options | Handler receives                                                                                             |
| ---------------------- | --------------- | ------------------------------------------------------------------------------------------------------------ |
| `onToolChange`         | —               | `ToolType \| null` — the newly selected tool, or `null` when no tool is active.                              |
| `onToolSettingsChange` | —               | `ToolSettingsChangeEvent` — a discriminated union: check the `tool` field to narrow to that tool's settings. |

For payload type details, follow each method's entry in the [API reference](https://developers.felt.com/js-sdk-api-reference).


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