title: Is there a way to add characters in dc.js numberDisplay Class?
body: <p>I would like to add some text in the numberDisplay function, a little bit like this.</p>
  
  <pre><code>    dc.numberDisplay('#duration')
          .group(all)
          .valueAccessor(function (d) { 
              if (xxx) return d.duration + ' [months]';
              else return d.duration + ' [years]'; 
          });
  </code></pre>
  
  <blockquote>
    <p>this prints <code>NaN</code></p>
  </blockquote>
  
  <p>My specific need is that I have a duration number in years, but sometimes —after some crossfiltering— this number gets really low —<em>e.g.</em> 0.00002— and that is not understandable so I would like to simplify things for the user and transform that in months or days or even hours.</p>
  
  <p>My first attempt was to split the duration in 4 numbers (years/months/days/hours) and have 4 separate html tags and 4 numberDisplay's. </p>
  
  <p>But that is not necessary if duration = 5 hours, the user will see <code>0Y, 0M, 0D, 5H</code>, while <code>5 hours</code> would be more clear.</p>
  
  <p>I need to print at least 2 informations: the highest nonzero number and the unit and I cannot manage that.</p>
  
  <p>Another idea: Is there a way to trigger a secondary function after the numberDisplay finished?<br>
  This way I could just send basic d.duration in years in the numberDisplay. And have another function transform that afterwards in smaller units.</p>
  
  <p>[EDIT]<br>
  <code>.html()</code> seems to be build for this, but <code>one/some/none</code> do not fit my needs of diferentiating  0.0000002 / 0.0002 / 0.02</p>