title: jQuery fullCalendar - extend buildCellHTML function?
body: <p>I want to extend <code>fullCalendar</code> in a way that it would show special dates names in their respective day cell. For example if user would define special date (in backend) <code>2017-12-25</code> and call it <code>Christmas</code>, by going into Calendar, he would see <code>Christmas</code> word on that cell (let say in top left corner).</p>
  
  <p>So looking into fullCalendar source, I can see that it builds those cells using this function:</p>
  
  <pre><code>function buildCellHTML(date) {
          var contentClass = tm + "-widget-content";
          var month = t.start.getMonth();
          var today = clearTime(new Date());
          var html = '';
          var classNames = [
              'fc-day',
              'fc-' + dayIDs[date.getDay()],
              contentClass
          ];
  
          if (date.getMonth() != month) {
              classNames.push('fc-other-month');
          }
          if (+date == +today) {
              classNames.push(
                  'fc-today',
                  tm + '-state-highlight'
              );
          }
          else if (date &lt; today) {
              classNames.push('fc-past');
          }
          else {
              classNames.push('fc-future');
          }
  
          html +=
              "&lt;td" +
              " class='" + classNames.join(' ') + "'" +
              " data-date='" + formatDate(date, 'yyyy-MM-dd') + "'" +
              "&gt;" +
              "&lt;div&gt;";
  
          if (showNumbers) {
              html += "&lt;div class='fc-day-number'&gt;" + date.getDate() + "&lt;/div&gt;";
          }
  
          html +=
              "&lt;div class='fc-day-content'&gt;" +
              "&lt;div style='position:relative'&gt;&amp;nbsp;&lt;/div&gt;" +
              "&lt;/div&gt;" +
              "&lt;/div&gt;" +
              "&lt;/td&gt;";
  
          return html;
      }
  </code></pre>
  
  <p>Now if I would directly modify fullCalendar library by adding this line:</p>
  
  <p><code>html += "&lt;div&gt;Placeholder&lt;/div&gt;"</code></p>
  
  <p><strong>Just before this:</strong> </p>
  
  <p><code>if (showNumbers) {
              html += "&lt;div class='fc-day-number'&gt;" + date.getDate() + "&lt;/div&gt;";
          }</code></p>
  
  <p>It does add what I basically need, but of course I do not want to modify library directly, I want to extend it. Looking into documentation, I can't seem to find how could I extend day cell content.</p>
  
  <p>And that function is inner function of another one, so I can't access it (or can I?). But maybe someone more experienced with fullCalendar, could shed some light how to do this extension?</p>
  
  <p>P.S. Note I'm talking about all day cells, not events (that has specific event attach to it). I mean it should just check if that day is special day no matter if there is event at that day or not (though actual special dates implementation in backend is in not relevant here). </p>
  
  <p>P.S.S. fullCalendar version I'm using is <code>1.6.4</code></p>