title: changing d3.JSON in Hierarchical Bars to JSON.parse
body: <p>I'm using <a href="http://bl.ocks.org/mbostock/1283663" rel="nofollow">http://bl.ocks.org/mbostock/1283663</a></p>
  
  <p>and I'm trying to change the following code </p>
  
  <pre><code>d3.json("readme.json", function(root) {
    hierarchy.nodes(root);
    x.domain([0, root.value]).nice();
    down(root, 0);
  });
  </code></pre>
  
  <p>to a JSON.parse (some data).  I don't have a problem pulling the JSON data but I am totally confused about what is being setup in the rest of the d3.json process with the hierarchy.node(root), x.domain and down(root)</p>