Ajax: Not able to detect event or console.log

Question

I am creating the event but not able to detect the event using Ajax. I am working on Codeigniter and I have the following code:-

View.php

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.0/jquery.min.js"></script>
<script>
$("#promocode").on("input",function(){
    console.log('handler detected');
    var valueModel = $(this).val();
    $.ajax({
      url : "bookings/getVCode",
      type: "post",
      data: {"valueModel":valueModel},
      success : function(data){
        // console.log(data);
        $("#msg").html(data);
      },
    });
});
</script>

<label for="promocode">Promo Code</label><div id="msg"></div>
 <input class="form-control"  type="text" id="promocode" name="promocode" >

My Controller:

Bookings.php

function getVCode()
{
    $data = $this->NewQuoteModel->checkVoucherexist();
    $option =""; 

    if(count($data) > 0){
        $option .="<p> Your Voucher is Valid! </p>"; 
    } else {
        $option .= "<p> Your Voucher is not Valid! </p>"; 
    }
            echo $option; 
}

And My Modal

NewQuoteModel.php

 function checkVoucherexist()
{
    $model = $this->input->post('valueModel');  
    $this->db->select('*'); 
    $this->db->from('Vouchers');
    $this->db->where('Name', $model);
    $query = $this->db->get();

    if ($query->num_rows() > 0) {
        return $query->result();
    } else {
        //echo 'No Make found';
    }

}