Get Month Name from Jquery Date Picker

HTML

<input>

JavaScript

$(document).ready(function(){
  //alert(getPreviousMonth(8));
  //ar timeZone=2018-06-27T04:00:00.000Z;
  getMonthNum('2015-03-04T00:00:00.000Z');
  })
    
  function getMonthNum(date){
   var formattedDate = new Date(date);
var d = formattedDate.getDate();
var m =  formattedDate.getMonth();
//m += 1;  // JavaScript months are 0-11
var y = formattedDate.getFullYear();

alert(m);
 }