index.html

<!DOCTYPE html>
<html>
<head>
    <style>
        html,
body,
#googleMap {
  height: 100%;
  width: 100%;
  margin: 0px;
  padding: 0px
}
    </style>
    </head>
<body>
    <script src="https://maps.googleapis.com/maps/api/js?key=puthereyourAPI&callback=initMap"></script>
<input type="file" name="file" id="file" onchange="handle_files(this.files)" />
<div id="googleMap"></div>
    <script type="text/javascript">
        var map;

function getCoor() {
  return coordinates;
}

function handle_files(files) {
  for (i = 0; i < files.length; i++) {
    file = files[i];
    console.log(file);
    var reader = new FileReader();
    ret = [];
    reader.onload = function(e) {
      console.log(e.target.result);
      var lines = e.target.result.split('\n');
      var bounds = new google.maps.LatLngBounds();
      for (var line = 0; line < lines.length; line++) {

        var point = lines[line].split(',');

        var count = 0;
        var coordinates = [];
        for (var dua = 0; dua < point.length; dua++) {
          if (dua % 2 == 0) {
            var latitude = point[dua];
          } else {
            var longitude = point[dua];
            coordinates[count] = new google.maps.LatLng(latitude/10000, longitude/10000);
            console.log(coordinates[count]);
            count++;
          }
        }
        var myTrip = [];
        for (var c = 0; c < coordinates.length; c++) {
          myTrip.push(coordinates[c]);
          bounds.extend(coordinates[c]);
        }
        map.fitBounds(bounds);

        //console.log(myTrip);
        var flightPath = new google.maps.Polyline({
          path: myTrip,
          strokeColor: "#0000FF",
          strokeOpacity: 0.8,
          strokeWeight: 8
        });

        flightPath.setMap(map);

      }

    }
    reader.onerror = function(stuff) {
      console.log("error", stuff);
      console.log(stuff.getMessage());
    }
    reader.readAsText(file); //readAsdataURL
  }

}

function initialize() {

  var mapProp = {

    center: new google.maps.LatLng(49.521911, 16.246056),
    zoom: 6,
    mapTypeId: google.maps.MapTypeId.ROADMAP
  };

  map = new google.maps.Map(document.getElementById("googleMap"), mapProp);
}

google.maps.event.addDomListener(window, 'load', initialize);
    </script>
</body>
</html>