I'm new in codeigniter and using such as javascript, jQuery, Ajax, etc. Just now, i'm trying to build an application like visitor management system, that usually takes barcode.

Here's my table on database:

tbl_vin

Here's my model:

public function selectX($tbl, $where)
{
    return $this->db->get_where($tbl, $where);
}

Here's my controller:

public function check_av_vin(){
  $vin = $this->input->post('f1');
  $where = array('Vin'=>$vin);
  $result = $this->crud_m->selectX('tbl_vin', $where);
  if($result->num_rows() > 0){
    echo "1";
  }else{
    echo "0";
  }
}

Here's my view:

<input class="form-control" type="text" name="f1" id="barcode" autofocus></input>

Here's my JS (on the same view):

$(document).ready(function() {
$("#barcode").on('keydown', function(event) {
  if (event.keyCode == 13) {
    var bc = $("#barcode").val();
    $.ajax({
      url: "<?php echo site_url('Lobby/check_av_vin')?>",
      data: {Vin : bc},
      type: 'POST',
      success: function(data){
        if(data == '1'){
          alert("VIN Already Exist!");
          $("#barcode").val("");
          $("#barcode").focus();
        }
        else if(data == '0'){
          alert("VIN available!");
          $("#barcode").val("");
          $("#barcode").focus();
        }
        else{
          alert("Error");
          $("#barcode").val("");
          $("#barcode").focus();
        }
      }
    });
    $("#name").focus();
    return false;
  }
});

The question is: Whatever i'm inserting the correct barcode like 'VIN00001' or wrong barcode or not inserting any text and hit enter, its always get data with string '0' and always get alert 'VIN available'. I dont know where's the problem. Please help me.