Consider extracting this to a method then the assignment can still be inline as are the others e.g.

```
var gogoduckConfig = {
    layerName = this._selectedLayerWfsLayerName()
    dateRangeStart: this._getDateFromPicker(this.startDateTimePicker),
    dateRangeEnd: this._getDateFromPicker(this.endDateTimePicker),
    productLatitudeRangeStart: productExtents.lat.min,
    productLongitudeRangeStart: productExtents.lon.min,
    productLatitudeRangeEnd: productExtents.lat.max,
    productLongitudeRangeEnd: productExtents.lon.max
};


_selectedLayerWfsLayerName: function() {
    var name;
    if (this.selectedLayer.wfsLayer) {
        name = this.selectedLayer.wfsLayer.name;
    }
    return name;
}
```