title: getmonth() is not a function error parsing date
body: <p>I have an object with a <code>production_date</code> which I'm trying to extract year and month but I keep getting <code>getMonth()</code> and <code>getYear()</code> is not a function error...</p>
  
  <pre><code>function(d) { 
            var dt = d.production_date
            var dtm = dt.getMonth();
            var dty = dt.getYear();
            return dtm + "/" + dty 
         }
  </code></pre>