title: Specifying the json file for some visualization via a dropdown box
body: <p>I've recently started trying out d3.js for visualization. I don't have much of a background in JS or web scripting, so sorry if this is an easy thing that I'm asking. </p>
  
  <p>The exact example doesn't matter too much. I am making a graph, something like <a href="http://mbostock.github.com/d3/ex/force.html" rel="nofollow">this</a></p>
  
  <p>I want there to be a drop down menu on the page that lists different data sources. The user could then select the data source and the graph would update.  </p>
  
  <p>I created a drop down menu using the example <a href="http://www.idocs.com/tags/linking/linking_famsupp_137.html" rel="nofollow">here</a>. However, I am unsure how to get the value as I need the line</p>
  
  <pre><code>d3.json("miserables.json", function(json) {
  </code></pre>
  
  <p>to update with the new name.</p>