Zoomable Circle Packing with color dropdown

forked from mbostock's block: Zoomable Circle Packing with color dropdown to show fill can be changed per circle's data

<!DOCTYPE html>
<meta charset="utf-8">
<head>
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>

.node {
      cursor: pointer;
    }

.node:hover {
      stroke: #000;
      stroke-width: 1.5px;
    }

.node--leaf {
      fill: white;
    }

.label {
      font: 11px "Helvetica Neue", Helvetica, Arial, sans-serif;
      text-anchor: middle;
      text-shadow: 0 1px 0 #fff, 1px 0 0 #fff, -1px 0 0 #fff, 0 -1px 0 #fff;
    }

.label,
    .node--root,
    .node--leaf {
      pointer-events: none;
    }

</style>
  
</head>
<body>
  
  <select id="select-color">
    <option value="greater">Greater than 1000</option>
    <option value="starts">Starts with A</option>
  </select>

var svg = d3.select("svg"),
        margin = 20,
        diameter = +svg.attr("width"),
        g = svg.append("g").attr("transform", "translate(" + diameter / 2 + "," + diameter / 2 + ")");

var color = d3.scaleLinear()
        .domain([-1, 5])
        .range(["hsl(152,10%,80%)", "hsl(228,10%,40%)"])
        .interpolate(d3.interpolateHcl);

var pack = d3.pack()
        .size([diameter - margin, diameter - margin])
        .padding(2);

d3.json("flare.json", function(error, root) {
      if (error) throw error;

root = d3.hierarchy(root)
          .sum(function(d) { return d.size; })
          .sort(function(a, b) { return b.value - a.value; });

var focus = root,
          nodes = pack(root).descendants(),
          view;

var node = g.selectAll("circle,text");

svg
          .style("background", color(-1))
          .on("click", function() { zoom(root); });

zoomTo([root.x, root.y, root.r * 2 + margin]);

function zoom(d) {
        var focus0 = focus; focus = d;

var transition = d3.transition()
            .duration(d3.event.altKey ? 7500 : 750)
            .tween("zoom", function(d) {
              var i = d3.interpolateZoom(view, [focus.x, focus.y, focus.r * 2 + margin]);
              return function(t) { zoomTo(i(t)); };
            });

transition.selectAll("text")
          .filter(function(d) { return d.parent === focus || this.style.display === "inline"; })
            .style("fill-opacity", function(d) { return d.parent === focus ? 1 : 0; })
            .on("start", function(d) { if (d.parent === focus) this.style.display = "inline"; })
            .on("end", function(d) { if (d.parent !== focus) this.style.display = "none"; });
      }

</script>
</body>
</html>

https://d3js.org/d3.v4.min.js