title: D3: Create a grouped bar chart from json objects
body: <p>I have some data like this:</p>
  
  <pre><code>[
   { id: 12, value1: "2.92", value2: "4.22", value3: "3.69" }
  , 
   { id: 23, value1: "2.69", value2: "4.24", value3: "3.77" }
  ,
    ....
  ]
  </code></pre>
  
  <p>I want to create a horizontal grouped bar chart, so that there are 3 groups of bars, first all value1 bars (labeled as Value1), followed by all value2 bars and finally all value3 bars.</p>
  
  <p>How can I do this - keeping in mind that the data will be updated dynamically in the future, so new data objects will be added and others will be removed. Guess I could use id as a key.</p>