Collapsible Tree data loading experiment

An example file to go alongside a question asked on Stack Overflow as to how to load a JSON array from an internal array rarther than import it as a file. The example here is a combination of Mike Bostocks Collapsible Tree example and a question asked on Stack Overflow on how to generate multi-level JSON formatted data.

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">

<title>Tree Example</title>

.node circle {
	  fill: #fff;
	  stroke: steelblue;
	  stroke-width: 1.5px;
	}

.node text {
	  font: 10px sans-serif;
	}

.link {
	  fill: none;
	  stroke: #ccc;
	  stroke-width: 1.5px;
	}
	
    </style>

</head>

<body>

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.min.js"></script>

var data = [
	 { "name" : "ABC", "parent":"DEF", "relation": "ghi", "depth": 1 },
	 { "name" : "DEF", "parent":"null", "relation": "null", "depth": 0 },
	 { "name" : "new_name", "parent":"ABC", "relation": "rel", "depth": 2 },
	 { "name" : "new_name2", "parent":"ABC", "relation": "foo", "depth": 2 },
	 { "name" : "Foo", "parent":"DEF", "relation": "rel", "depth": 2 }
	];

// *********** Convert flat data into a nice tree ***************
// create a name: node map
var dataMap = data.reduce(function(map, node) {
	map[node.name] = node;
	return map;
}, {});

// create the tree array
var treeData = [];
data.forEach(function(node) {
	// add to parent
	var parent = dataMap[node.parent];
	if (parent) {
		// create child array if it doesn't exist
		(parent.children || (parent.children = []))
			// add node to child array
			.push(node);
	} else {
		// parent is null or missing
		treeData.push(node);
	}
});

// show what we've got
d3.select('#area1').append('pre')
    .text(JSON.stringify(treeData, null, '  '));

// ************** Generate the tree diagram	 *****************
var margin = {top: 20, right: 120, bottom: 20, left: 120},
	width = 960 - margin.right - margin.left,
	height = 500 - margin.top - margin.bottom;
	
var i = 0,
	duration = 750,
	root;

var tree = d3.layout.tree()
	.size([height, width]);

var diagonal = d3.svg.diagonal()
	.projection(function(d) { return [d.y, d.x]; });

var svg = d3.select("#area2").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 + ")");

d3.json("example.json", function(error, DEF) {
  root = DEF;
  root.x0 = height / 2;
  root.y0 = 0;

function collapse(d) {
	if (d.children) {
	  d._children = d.children;
	  d._children.forEach(collapse);
	  d.children = null;
	}
  }
  
  root.children.forEach(collapse);
  update(root);
});

d3.select(self.frameElement).style("height", "800px");

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 * 180; });

// Update the nodes…
  var node = svg.selectAll("g.node")
	  .data(nodes, function(d) { return d.id || (d.id = ++i); });

// Enter any new nodes at the parent's previous position.
  var nodeEnter = node.enter().append("g")
	  .attr("class", "node")
	  .attr("transform", function(d) { return "translate(" + source.y0 + "," + source.x0 + ")"; })
	  .on("click", click);

nodeEnter.append("circle")
	  .attr("r", 1e-6)
	  .style("fill", function(d) { return d._children ? "lightsteelblue" : "#fff"; });

nodeEnter.append("text")
	  .attr("x", function(d) { return d.children || d._children ? -10 : 10; })
	  .attr("dy", ".35em")
	  .attr("text-anchor", function(d) { return d.children || d._children ? "end" : "start"; })
	  .text(function(d) { return d.name; })
	  .style("fill-opacity", 1e-6);

// Transition nodes to their new position.
  var nodeUpdate = node.transition()
	  .duration(duration)
	  .attr("transform", function(d) { return "translate(" + d.y + "," + d.x + ")"; });

nodeUpdate.select("circle")
	  .attr("r", 4.5)
	  .style("fill", function(d) { return d._children ? "lightsteelblue" : "#fff"; });

nodeUpdate.select("text")
	  .style("fill-opacity", 1);

// Transition exiting nodes to the parent's new position.
  var nodeExit = node.exit().transition()
	  .duration(duration)
	  .attr("transform", function(d) { return "translate(" + source.y + "," + source.x + ")"; })
	  .remove();

nodeExit.select("circle")
	  .attr("r", 1e-6);

nodeExit.select("text")
	  .style("fill-opacity", 1e-6);

// Update the links…
  var link = svg.selectAll("path.link")
	  .data(links, function(d) { return d.target.id; });

// Enter any new links at the parent's previous position.
  link.enter().insert("path", "g")
	  .attr("class", "link")
	  .attr("d", function(d) {
		var o = {x: source.x0, y: source.y0};
		return diagonal({source: o, target: o});
	  });

// Transition links to their new position.
  link.transition()
	  .duration(duration)
	  .attr("d", diagonal);

// Transition exiting nodes to the parent's new position.
  link.exit().transition()
	  .duration(duration)
	  .attr("d", function(d) {
		var o = {x: source.x, y: source.y};
		return diagonal({source: o, target: o});
	  })
	  .remove();

// Stash the old positions for transition.
  nodes.forEach(function(d) {
	d.x0 = d.x;
	d.y0 = d.y;
  });
}

// Toggle children on click.
function click(d) {
  if (d.children) {
	d._children = d.children;
	d.children = null;
  } else {
	d.children = d._children;
	d._children = null;
  }
  update(d);
}

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

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.min.js