d3article-en4.3

function voronoiMouseover(d) {
  legendsDate.text(timeFormatter(d.data.date));

  legendsValues.text(dataItem => {
    const value = percentsByDate[d.data.date][dataItem];

    return value ? value + '%' : 'N.A.';
  });

  d3.select(`#region-${ d.data.regionId }`).classed('region-hover', true);

  hoverDot
    .attr('cx', () => rescaledX(d.data.date))
    .attr('cy', () => rescaledY(d.data.percent));
}