Diff is not a function in Moment.js
<p>I am selecting a date in the Air Datepicker and trying to compare today's date to the selected date to determine the difference in days. So, for example, if today is 12/11/2016 and I select 12/20/2016, I want to get the difference, which is 9. </p>

<p>I keep running into the following error: "end.diff is not a function".</p>

<p>I've stripped the following code down to the essentials:</p>

<p><strong>HTML</strong></p>

<pre><code>&lt;form&gt;
    &lt;input id="datereq" name="datereq" type="text" class="dateReq" value="" /&gt;
&lt;/form&gt;
&lt;div id="selected"&gt;&lt;/div&gt;
</code></pre>

<p><strong>JQUERY</strong></p>

<pre><code> var date = new Date(),
     disabledDays = [0, 6];

 $('.dateReq').datepicker({
     dateFormat: 'mm/dd/yyyy',
     minDate: new Date(),
     language: 'en',
     autoClose: true,
     onRenderCell: function(date, cellType) {
         if (cellType == 'day') {
             var day = date.getDay(),
                 isDisabled = disabledDays.indexOf(day) != -1;
             return {
                 disabled: isDisabled
             };
         }
     },

     // Display Appropriate Order Type Options
     onSelect: function onSelect(fd, date) {
         var now = moment(new Date()).format('MM/DD/YYYY'),
             end = fd,
             days = end.diff(now, 'days');
         $('#selected').html('now:' + now + 'end:' + end + 'diff:' + days);
         //console.log('end:' + end);
         //console.log('diff:' + days);
     }
 });
</code></pre>

<p><strong>Fiddle</strong></p>

<p><a href="https://jsfiddle.net/qn530dpq/" rel="noreferrer">https://jsfiddle.net/qn530dpq/</a></p>