title: Adding minutes to datetime in momentjs
body: <p>I need to add the variable <code>secondsToMinutes</code> to the <code>startdate</code>. </p>
  
  <p><code>secondsToMinutes</code> is "3:20"
  <code>startDate</code> = "2:00 PM"
  <code>endDate</code> should equal "2:03:20 PM".
  I've tried a number of ways and get errors each and every time.</p>
  
  <pre><code>   var startdate = data.StartTime;
     startdate = moment(startdate).format('LTS');
  
     var secondsToMinutes = readableDuration(self.runlength());//='3:20';
  
     var seconds = secondsToMinutes.split(':')[1];
     var minutes = secondsToMinutes.split(':')[0];
  
     var date = moment(startdate)
          .add(seconds, 'seconds')
          .add(minutes, 'minutes')
          .format('LTS');
  </code></pre>
  
  <p>Date shows up as invalid date.</p>