d3article3.2

const filteredData = data.filter(dataItem => enabledRegionsIds.indexOf(dataItem.regionId) >= 0);

const voronoiPaths = voronoiGroup.selectAll('path')
  .data(voronoi.polygons(filteredData));

voronoiPaths.exit().remove();

voronoiPaths
  .enter()
  .append('path')
  .merge(voronoiPaths)
  .attr('d', d => (d ? `M${ d.join('L') }Z` : null))
  .on('mouseover', voronoiMouseover)
  .on('mouseout', voronoiMouseout)
  .on('click', voronoiClick);