Country->state->city using 'Jquery Ajax' in codeigniter

Country State City Flow In Codeigniter Using Jquery Ajax

My Controller's Function Code:-

                //STATE

public function state($id)

  {

$this->load->model('admin/model');

$where=array("country_id"=>$id);

//print_r ($where); break;

  $state=$this->model->sel_where('state',$where);

 echo "<option>-State-</option>";

 foreach($state as $row)

 {

echo"<option value='".$row['state_id']."'>".$row['state_name']."</option>";  

 }

}

//city

public function city($id)

  {

$this->load->model('admin/model');

$where=array("state_id"=>$id);

//print_r ($where); break;

  $city=$this->model->sel_where('city',$where);

 echo "<option>-City-</option>";

 foreach($city as $ct)

 {

echo"<option value='".$ct['city_id']."'>".$ct['city_name']."</option>";  

 }

}

My Model's Function Code:-

//select data with id  

public function sel_where($tbl,$where)

{

$r=$this->db->get_where($tbl,$where);

$rr= $r->result_array();

//print_r($rr);break;

return $rr;

}

My View's Html Code:-

<script src="https://code.jquery.com/jquery-1.9.1.min.js" type="text/javascript"></script>

<script>

    

var state,city;

function change_state()

{

state=$('#country_id').val();

$('#state_id').load('<?php echo base_url();?>index.php/admin/user/state/'+state);

}

function change_city()

{

city=$('#state_id').val();

$('#city_id').load('<?php echo base_url();?>index.php/admin/user/city/'+city);

}

</script>

<label>Select Country</label>

<select id="country_id" name="country" onChange="change_state();">

    <option >Country</option>

          <?php foreach($cnt as $c)

 { ?>

          <option value="<?php echo $c['country_id'];?>"><?php echo $c['country_name'];?></option> <?php }?> </select>

<!--State-->

  <label>Select State</label>

   <select id="state_id" name="state"  onChange="change_city();">

       <option >-State-</option>

        </select>

<!--City-->

       <label >Select City</label>

             <select id="city_id" name="city" >

               <option>-city-</option>

           </select>