Date Difference

HTML

<script src="https://rawgithub.com/timrwood/moment/2.1.0/min/moment.min.js"></script>
<div class="wrap">
  <input type="text" id="appointment" placeholder="Appointment Date" />
  <br />
  <input type="text" id="birthdate" placeholder="Date of Birth" />
  <br />
  <input type="submit" id="submit" />
</div>
<div id="result" class="wrap">Valid/Invalid</div>
<div id="result1" class="wrap">dvDate</div>
<div id="result2" class="wrap">curDate</div>
<div id="result3" class="wrap">dvDate - curDate</div>
<div id="note">
  <p>This is using the Moment.JS library.</p>
</div>

CSS

* {
  margin: 0;
  padding: 0;
}

body {
  width: 95%;
  padding: 2.5%;
}

.wrap {
  padding: 1em;
  border-radius: 6px;
  background: #eee;
}

#result {
  margin: 1em 0 0 0;
  text-align: center;
}

#note {
  width: 100%;
  text-align: center;
  position: absolute;
  bottom: 5px;
  display: block
}

JavaScript

// Counts Months - Disregards Days
function monthDiff(d1, d2) {
  var months;
  months = (d2.getFullYear() - d1.getFullYear()) * 12;
  months -= d1.getMonth() + 1;
  months += d2.getMonth();
  return months <= 0 ? 0 : months;
}

$('#submit').on('click', function() {
  var month = ["JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG", "SEP", "OCT", "NOV", "DEC"];

  var b;
  var yyyy = 2016;
  var curVal = "01DEC";
  var dvVal = "01APR";
  var dd = dvVal.substr(0, 2);
  var mm = dvVal.substr(2, 3);
  var dd1 = curVal.substr(0, 2);
  var mm1 = curVal.substr(2, 3);
  
  var d = new Date();

  var dvDate = new Date(yyyy, month.indexOf(mm.toUpperCase()), dd);
  var curDate = new Date(yyyy, month.indexOf(mm1.toUpperCase()), dd1);
  
  var timeDiff = dvDate.getTime() - curDate.getTime();
  var diffDays = Math.ceil(timeDiff / (1000 * 3600 * 24));
   
   if(diffDays > 120)
   {
      dvDate = new Date(yyyy-1, month.indexOf(mm.toUpperCase()), dd);
   }
   if(diffDays < -240)
   {
      dvDate = new Date(yyyy+1, month.indexOf(mm.toUpperCase()), dd);
   }
   
   if (dvDate < curDate)
   {
       b = false;
   }
   else
   {
      b = true;
   }

  
  $('#result1').text(dvDate);
  $('#result2').text(curDate);
  $('#result3').text(diffDays);
  $('#result').text(b);
});