JAVASCRIPT

f.select on change jquery

$('select').on('change', function() {
  alert( this.value );
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<select>
    <option value="1">One</option>
    <option value="2">Two</option>
</select>

trigger change select element jquery

$('#selectField').val(10).trigger('change');

or

$('#selectField').val(10).change();