title: d3js transition step function
body: <p>I am using transitions in d3js and it works fine. However, is there a way to fire a function everytime the object position is updated? (for every step)</p>
  
  <p>Here is a some fake code:</p>
  
  <pre><code>obj.transition()
    .ease('quad')
    .durantion(250)
    .attr('cy', function(d) {
      return d*d;
     });
  </code></pre>
  
  <p>I know that if you put the each(type, fn) you can get the events from end and start. But no step is available.</p>
  
  <pre><code>obj.transition()
    .ease('quad')
    .duration(250)
    .attr('cy', function(d) {
      return d*d;
     })
    .each('start', function(d) { console.log('x'); });
  </code></pre>
  
  <p>Is there a way to do this?</p>