Untitled

<html>
<select>
    <option value="1">One</option>
    <option value="2">Two</option>
</select>
<input type="text" name="bal" id="textbal" />
<script type="text/javascript">
        $('select').on('change', function() {
          $('#textbal').val( this.value );
          var a = this.value;
          alert(a);

          $('#textball').attr('value',a);

        });
$('textball').trigger('change', function() {
        //  alert( this.val() );
         // alert( $(this).val() );
          alert('hi');
        });
</script>
</html>