I want to combine three javascript variable and display this in a textbox as default value

html code for form

<form action="code.php" method="POST" enctype="multipart/form-data">
    <div class="form-group col-md-12 mb-2">
    <label for="fname" class="form-label">Select District Name<span class="font-weight-bold text-danger">*</span></label>
    <select id="dist" name="distcode" class="form-select" require>
        <option class="active">Select District Name</option>
        <?php
            include '../mysqli_connect.php';
            $sql = "SELECT * FROM tb_district";
            $result = $con->query($sql);
            if ($result->num_rows > 0) { 
                // output data of each row
                while($row = $result->fetch_assoc()) { 
                    ?>

                    <option value="<?php echo $row['dist_code']; ?>"><?php echo $row['dist_name']; ?></option>";
                    <?php
                }
            } 
        ?>
    </select>
    </div>

    <div class="form-group col-md-12 mb-2">
        <label for="fname" class="form-label">Select Block Name<span class="font-weight-bold text-danger">*</span></label>
        <select id="block" name="blockname" class="form-select">
            <option class="active">Select Block Name</option>
        </select>
    </div>

    <div class="form-group col-md-12 mb-3">
        <label for="fname" class="form-label">Select Panchayat Name<span class="font-weight-bold text-danger">*</span></label>
        <select id="panchayat" name="panchayatname" class="form-select">
            <option class="active">Select Panchayat</option>
        </select>
    </div>
    
    <div class="form-group col-md-12 mb-2">
        <label for="fname" class="form-label">USERID<span class="font-weight-bold text-danger">*</span></label>
        <input type="text" class="form-control" id="panchayat" name ="blockcode"  readonly >
    </div>

    <div class="form-group col-md-12">
        <button type="submit" name="save_excel_data" class="btn btn-primary mt-3">Import</button>
    </div>
</form>

And the Javascript for load dependent dropdown list is

$('#dist').click(function() {
    //Get selected Country ID
    var distid = $(this).val();
    $.ajax({
          type      : 'POST',
          url       : '../adddistblockpanchayat/load-distblockajax.php',
          data      : 'dist='+distid, //pass country data
          success   : function(data) {
               $('#block').html(data);
          }
     });
});

$('#block').click(function() {
    //Get selected Country ID
    var blockid = $(this).val();
    $.ajax({
       type      : 'POST',
       url       : '../adddistblockpanchayat/load-distblockajax.php',
       data      : 'block='+blockid, //pass country data
       success   : function(data) {
             $('#panchayat').html(data);
         }
    });
});

now I want to combine the value of the dependent dropdown and display this is a textbox.