function getDateArray (start, end) {

        var arr = [];

        var startDate = new Date(start);

        var endDate = new Date(end);

        while (startDate <= endDate) {

            arr.push(new Date(startDate.setMonth(startDate.getMonth() + 1)));

            }

        return arr;

    }

function test  (){   

​

     var z = "2018-09-01"; var y = "2019-09-10"

     var dateArr = getDateArray(z, y);

     alert(dateArr[0] + "\n" + dateArr[1] + "\n" + dateArr[2]);

  alert(daysBetween(dateArr[0], dateArr[3]));

  calculateFinalArray(dateArr);

}

​

function daysBetween ( date1, date2 ) 

{   

  var timeDiff = Math.abs(date2.getTime() - date1.getTime());

 return dayDifference = Math.ceil(timeDiff / (1000 * 3600 * 24)); 

 } 

​

function calculateFinalArray(dateArr){

  var dayCounts = "";

   for (var x = 0; x < dateArr.length-1;x++)

     {

       dayCounts += daysBetween(dateArr[x],dateArr[x+1]) + ":";

     }

  alert(dayCounts);

}