I'm using fullCalendar and I want to use the start variable from the "select" callback as a PHP variable.

This is my JavaScript:

```
select: function(start, end) {
  $('#ModalAdd #start').val(moment(start).format('YYYY-MM-DD '));
  $('#ModalAdd #end').val(moment(end).format('YYYY-MM-DD '));
  $('#ModalAdd').modal('show');

  var start = val(moment(start).format('YYYY-MM-DD ')) ;
  $.ajax({
    type: 'POST',
    data: {start:start},
  });
},

```

This is my PHP script :

```
<?php
if( isset($_POST['start']) ){
  $start = $_POST['start'];
  echo json_encode($start);
}
else echo "string";
?>

```

This is my HTML input:

```
<input type="text" name="start" class="form-control" id="start" readonly>

```

but I get "string" as a result.