1$(document).ready(function() {
2    $("#gate option[value='Gateway 2']").prop('selected', true);
3    // you need to specify id of combo to set right combo, if more than one combo
4});
5

1$('select').on('change', function() {
2  alert( this.value );
3});

1$('select option[value=8272]').attr('selected', '');

1$('#ddlID').val('New_OptionValue').change()

1$("#mySelectElementID").val("my_new_value"); //change selected option/value with jQuery
2

1    $('#choose').change(function(event) {
2        $.post('info.php', { selected: $('#choose').val() },
3            function(data) {
4                $('#update').html(data);
5            }
6        );            
7    });