D3 Examples - Dice roll sample space

Dice roll sample space
This is a simple d3.js tree diagram, arranged so that the tree is vertical, as used as an example in the book D3 Tips and Tricks.
It is derived from the Mike Bostock Collapsible tree example but it is a VERY cut down version without the ability to update (collapse).
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<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
​
    <title>Collapsible Tree Example</title>
​
    <style>
​
    .node circle {
      fill: #fff;
      stroke: steelblue;
      stroke-width: 3px;
    }
​
    .node text { font: 12px sans-serif; }
​
    .link {
      fill: none;
      stroke: #ccc;
      stroke-width: 2px;
    }
    
    </style>
​
  </head>
​
  <body>
    <button>roll</button>
    <span id="roll-value"></span>
​
<!-- load the d3.js library --> 
<script src="https://d3js.org/d3.v3.min.js"></script>
    
<script>
​
var treeData = [
  {
    "value": "Top Level",
    "parent": "null",
    "children": [
      {
        "value": "1",
        "parent": "Top Level",
        "children": [
          {
            "value": "1",
            "parent": "Level 2: 1"
          },
          {
            "value": "2",
            "parent": "Level 2: 1"
          },
          {
            "value": "3",
            "parent": "Level 2: 1"
          },
          {
            "value": "4",
            "parent": "Level 2: 1"
          },
          {
            "value": "5",
            "parent": "Level 2: 1"
          },
          {
            "value": "6",
            "parent": "Level 2: 1"
          }
        ]
      },
      {
        "value": "2",
        "parent": "Top Level",
        "children": [
          {
            "value": "1",
            "parent": "Level 2: 2"
          },
          {
            "value": "2",
            "parent": "Level 2: 2"
          },
          {
            "value": "3",
            "parent": "Level 2: 2"
          },
          {
            "value": "4",
            "parent": "Level 2: 2"
          },
          {
            "value": "5",
            "parent": "Level 2: 2"
          },
          {
            "value": "6",
            "parent": "Level 2: 2"
          }
        ]
      },
      {
        "value": "3",
        "parent": "Top Level",
        "children": [
          {
            "value": "1",
            "parent": "Level 2: 3"
          },
          {
            "value": "2",
            "parent": "Level 2: 3"
          },
          {
            "value": "3",
            "parent": "Level 2: 3"
          },
          {
            "value": "4",
            "parent": "Level 2: 3"
          },
          {
            "value": "5",
            "parent": "Level 2: 3"
          },
          {
            "value": "6",
            "parent": "Level 2: 3"
          }
        ]
      },
      {
        "value": "4",
        "parent": "Top Level",
        "children": [
          {
            "value": "1",
            "parent": "Level 2: 4"
          },
          {
            "value": "2",
            "parent": "Level 2: 4"
          },
          {
            "value": "3",
            "parent": "Level 2: 4"
          },
          {
            "value": "4",
            "parent": "Level 2: 4"
          },
          {
            "value": "5",
            "parent": "Level 2: 4"
          },
          {
            "value": "6",
            "parent": "Level 2: 4"
          }
        ]
      },
      {
        "value": "5",
        "parent": "Top Level",
        "children": [
          {
            "value": "1",
            "parent": "Level 2: 5"
          },
          {
            "value": "2",
            "parent": "Level 2: 5"
          },
          {
            "value": "3",
            "parent": "Level 2: 5"
          },
          {
            "value": "4",
            "parent": "Level 2: 5"
          },
          {
            "value": "5",
            "parent": "Level 2: 5"
          },
          {
            "value": "6",
            "parent": "Level 2: 5"
          }
        ]
      },
      {
        "value": "6",
        "parent": "Top Level",
        "children": [
          {
            "value": "1",
            "parent": "Level 2: 6"
          },
          {
            "value": "2",
            "parent": "Level 2: 6"
          },
          {
            "value": "3",
            "parent": "Level 2: 6"
          },
          {
            "value": "4",
            "parent": "Level 2: 6"
          },
          {
            "value": "5",
            "parent": "Level 2: 6"
          },
          {
            "value": "6",
            "parent": "Level 2: 6"
          }
        ]
      },
    ]
  }
];
​
// ************** Generate the tree diagram  *****************
var margin = {top: 40, right: 120, bottom: 20, left: 120},
    width = 960 - margin.right - margin.left,
    height = 500 - margin.top - margin.bottom;
    
var i = 0;
​
var tree = d3.layout.tree()
    .size([height, width]);
​
var diagonal = d3.svg.diagonal()
    .projection(function(d) { return [d.x, d.y]; });
​
var svg = d3.select("body").append("svg")
    .attr("width", width + margin.right + margin.left)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
  
var root = treeData[0];
var currentNode = root;
  
function randomRoll () {
  return Math.ceil(Math.random() * 6);
}
  
var btn = d3.select("button");
var depthValue = 1;
var parentValue = "Top Level";
btn.on("click", function () {
  var roll = randomRoll();
  d3.select("#roll-value").text(roll);
  var selectedNode = d3.selectAll("g.node")
    .filter(function (d) {
        return d.value == roll && d.depth == depthValue && d.parent.value == parentValue;
      });
  selectedNode.selectAll("circle").style({stroke: "red"});
  depthValue++;
  parentValue = roll;
});
  
update(root);
​
function update(source) {
​
  // Compute the new tree layout.
  var nodes = tree.nodes(root).reverse(),
      links = tree.links(nodes);
​
  // Normalize for fixed-depth.
  nodes.forEach(function(d) { d.y = d.depth * 100; });
​
  // Declare the nodes…
  var node = svg.selectAll("g.node")
      .data(nodes, function(d) { return d.id || (d.id = ++i); });
​
  // Enter the nodes.
  var nodeEnter = node.enter().append("g")
      .attr("class", "node")
      .attr("transform", function(d) { 
          return "translate(" + d.x + "," + d.y + ")"; });
​
  nodeEnter.append("circle")
      .attr("r", 10)
      .style("fill", "#fff");
​
  nodeEnter.append("text")
      .attr("y", function(d) { 
          return d.children || d._children ? -18 : 18; })
      .attr("dy", ".35em")
      .attr("text-anchor", "middle")
      .text(function(d) { return d.value; })
      .style("fill-opacity", 1);
​
  // Declare the links…
  var link = svg.selectAll("path.link")
      .data(links, function(d) { return d.target.id; });
​
  // Enter the links.
  link.enter().insert("path", "g")
      .attr("class", "link")
      .attr("d", diagonal);
​
}
​
</script>
    
  </body>
</html>
​
    