Edit in JSFiddle

<div id="heatmap-example-1" class="cdv-heatmap"></div>
<div class="caption">World Rapid Chess Championship 2015, square utilization by white (how many times a piece landed on a square)</div>

d3.json('https://ebemunk.com/chess-dataviz/data/wrc.json', function(err, data) {
  var heatmapExample1 = new ChessDataViz.HeatMap('#heatmap-example-1', null, data.heatmaps.squareUtilization);
});