download csv with datepicker

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.0/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.24.0/moment.min.js"></script>


<script type="text/javascript" src="https://cdn.jsdelivr.net/npm/daterangepicker/daterangepicker.min.js"></script>
<link rel="stylesheet" type="text/css" href="https://cdn.jsdelivr.net/npm/daterangepicker/daterangepicker.css" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js"></script>

<script type="text/javascript" src="https://github.com/douglascrockford/JSON-js/raw/master/json2.js"></script>



    <ol class="breadcrumb">data from date : <input type="text" name="datefilter" value="" /></ol>
    <p>Click this button to download all data from node 1</p>
  <div>
    <button id="button1" class="button"><span>Download</span></button>
  </div>

JavaScript

$(function() {

$('input[name="datefilter"]').daterangepicker({
        showDropdowns : true,
    autoUpdateInput: false,
    locale: {
        cancelLabel: 'Clear'
    }
});
let filteredData;
$('input[name="datefilter"]').on('apply.daterangepicker', function(ev, picker) {
    $(this).val(picker.startDate.format('YYYY-MM-DD') + ' - ' + picker.endDate.format('YYYY-MM-DD'));
var startDate = picker.startDate.format('YYYY-MM-DD');
var endDate = picker.endDate.format('YYYY-MM-DD');
if (startDate != '' && endDate != '') {
          console.log(startDate, endDate);
          var endpoint = 'https://gmlews.com/api/data/?node_id=1';

$.ajax({
  method: "GET",
  url: endpoint,
  data: {
    startDate: startDate,
    endDate: endDate
  },
  success: function(data){
  var data = data;
  filteredData = _.filter(data, function(data){ 
    return (data.timestamp > startDate &&  
        data.timestamp < endDate)
});
console.log(filteredData);
} //function(data)end
}) //ajax end
} //if function end

$('input[name="datefilter"]').on('cancel.daterangepicker', function(ev, picker) {
    $(this).val('');
});

}); //apply button end
//download button
$("#button1").on('click', function(e) {
// JSON to CSV Converter
        function ConvertToCSV(objArray) {
     //   console.log(typeof objArray, objArray)
            var array = typeof objArray != 'object' ? JSON.parse(objArray) : objArray;
      //      console.log("YO", array)
            var str = '';

            for (var i = 0; i < array.length; i++) {
                var line = '';
                for (var index in array[i]) {
                    if (line != '') line += ','

                    line += array[i][index];
                }

                str += line + '\r\n';
            }

            return str;
        }
        var jsonObject = JSON.stringify(filteredData);
     
				var csv = ConvertToCSV(jsonObject)
         var a = document.createElement("a")
         var blob = new Blob([csv])
         a.download =...