Get next previous date

gistfile1.js

//using  jquery date picker

function getPreviousDay(event){
  event.preventDefault();
  var currDate = $('#date_box').val();
      currDate = $.datepicker.parseDate('mm/dd', currDate);
      
  var d = currDate.getDate();
  var m = currDate.getMonth();
  var y = currDate.getFullYear();
   
  var prevDay = new Date(y, m, d - 1);
      prevDay = prevDay.getMonth() + 1 + "/" + prevDay.getDate(); // +"/"+NextDate.getFullYear();
      
  return prevDay;
}


function getNextDay(event){ 
  event.preventDefault();
  var currDate = $('#date_box').val();
      currDate = $.datepicker.parseDate('mm/dd', currDate);
      
  var d = currDate.getDate();
  var m = currDate.getMonth();
  var y = currDate.getFullYear();
   
  var nextDay = new Date(y, m, d + 1);
      nextDay = nextDay.getMonth() + 1 + "/" + nextDay.getDate(); // +"/"+NextDate.getFullYear();
      
  return nextDay;
}

function getPreviousMonth(event){
  event.preventDefault();
  var currDate = $('#date_box').val();
      currDate = $.datepicker.parseDate('mm/dd', currDate);
      
  var d = currDate.getDate();
  var m = currDate.getMonth();
  var y = currDate.getFullYear();
   
  var prevMonth = new Date(y, m - 1, d);
      prevMonth = prevMonth.getMonth() + 1 + "/" + prevMonth.getDate(); // +"/"+NextDate.getFullYear();
      
  return prevMonth;
}

function getNextMonth(event){
  event.preventDefault();
  var currDate = $('#date_box').val();
      currDate = $.datepicker.parseDate('mm/dd', currDate);
      
  var d = currDate.getDate();
  var m = currDate.getMonth();
  var y = currDate.getFullYear();
   
  var prevMonth = new Date(y, m + 1, d);
      prevMonth = prevMonth.getMonth() + 1 + "/" + prevMonth.getDate(); // +"/"+NextDate.getFullYear();
      
  return prevMonth;
}