JSFiddle - React, Tailwind, and code Playground

HTML

<script>
    var root = {
 "name": "flare",
 "children": [
  {
   "name": "analytics",
   "children": [
    {
     "name": "cluster",
     "children": [
      {"name": "AgglomerativeCluster", "size": 3938},
      {"name": "CommunityStructure", "size": 3812},
      {"name": "HierarchicalCluster", "size": 6714},
      {"name": "MergeEdge", "size": 743}
     ]
    },
    {
     "name": "graph",
     "children": [
      {"name": "BetweennessCentrality", "size": 3534},
      {"name": "LinkDistance", "size": 5731},
      {"name": "MaxFlowMinCut", "size": 7840},
      {"name": "ShortestPaths", "size": 5914},
      {"name": "SpanningTree", "size": 3416}
     ]
    },
    {
     "name": "optimization",
     "children": [
      {"name": "AspectRatioBanker", "size": 7074}
     ]
    }
   ]
  },
  {
   "name": "animate",
   "children": [
    {"name": "Easing", "size": 17010},
    {"name": "FunctionSequence", "size": 5842},
    {
     "name": "interpolate",
     "children": [
      {"name": "ArrayInterpolator", "size": 1983},
      {"name": "ColorInterpolator", "size": 2047},
      {"name": "DateInterpolator", "size": 1375},
      {"name": "Interpolator", "size": 8746},
      {"name": "MatrixInterpolator", "size": 2202},
      {"name": "NumberInterpolator", "size": 1382},
      {"name": "ObjectInterpolator", "size": 1629},
      {"name": "PointInterpolator", "size": 1675},
      {"name": "RectangleInterpolator", "size": 2042}
     ]
    },
    {"name": "ISchedulable", "size": 1041},
    {"name": "Parallel", "size": 5176},
    {"name": "Pause", "size": 449},
    {"name": "Scheduler", "size": 5593},
    {"name": "Sequence", "size": 5534},
    {"name": "Transition", "size": 9201},
    {"name": "Transitioner", "size": 19975},
    {"name": "TransitionEvent", "size": 1116},
    {"name": "Tween", "size": 6006}
   ]
  },
  {
   "name": "data",
   "children": [
    {
     "name": "converters",
     "children": [
      {"name": "Converters", "size": 721},
      {"name":...

CSS

.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;
}

.hidden {
     display: none;   
}
}

JavaScript

var margin = 20,
    diameter = 500;

var color = d3.scale.linear()
    .domain([-1, 5])
    .range(["hsl(152,80%,80%)", "hsl(228,30%,40%)"])
    .interpolate(d3.interpolateHcl);

var pack = d3.layout.pack()
    .padding(2)
    .size([diameter - margin, diameter - margin])
    .value(function(d) { return d.size; })

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

//d3.json("flare.json", function(error, root) {
  //if (error) return console.error(error);

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

  var circle = svg.selectAll("circle")
      .data(nodes)
    .enter().append("circle")
      .attr("class", function(d) { return d.parent ? d.children ? "node" : "node node--leaf" : "node node--root"; })
      .style("fill", function(d) { return d.children ? color(d.depth) : null; })
      .on("click", function(d) { if (focus !== d) zoom(d), d3.event.stopPropagation(); });
  
//******************************my code********************
//hide/remove children from svg
var node = svg.selectAll("circle");
    node.filter(function(d){return d.depth >= 3}).classed("hidden", true);

//hide parent of hidden children (dark blue circles without white dots)
//TO-DO
svg.selectAll(".hidden").filter(function(d){return d.parent }).classed("hidden", true);

//calculate new position
//TO-DO

//***********************end of my code********************


  d3.select("body")
      .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)); };
 ...