# Module: ol/format/TopoJSON

This documentation is for OpenLayers v10.9.0. The latest is v.

## ol/format/TopoJSON

### Classes

TopoJSON

### Type Definitions

#### Options{Object}

  ##### Properties:

  Name | Type | Description
  --- | --- | ---
  `dataProjection` | ProjectionLike (defaults to 'EPSG:4326') | Default data projection.
  `layerName` | string | undefined | Set the name of the TopoJSON topology `objects`'s children as feature property with the specified name. This means that when set to `'layer'`, a topology like
      {
        "type": "Topology",
        "objects": {
          "example": {
            "type": "GeometryCollection",
            "geometries": []
          }
        }
      }
  will result in features that have a property `'layer'` set to `'example'`. When not set, no property will be added to features.
  `layers` | Array.<string> | undefined | Names of the TopoJSON topology's `objects`'s children to read features from. If not provided, features will be read from all children.

#### TopoJSONMultiPolygon{module:topojson-specification~Topology}