Select next option with jQuery

$('#fieldNext').click(function() {
    $('#selectionChamp option:selected').next().attr('selected', 'selected');

    alert($('#selectionChamp').val());      
});

Better answer by @VisioN: https://stackoverflow.com/a/11556661/1533609

$("#fieldNext").click(function() {
    $("#selectionChamp > option:selected")
        .prop("selected", false)
        .next()
        .prop("selected", true);
});​

DEMO: http://jsfiddle.net/w9kcd/1/

$(function(){
  $('#button').on('click', function(){
    var selected_element = $('#selectionChamp option:selected');
    selected_element.removeAttr('selected');
    selected_element.next().attr('selected', 'selected');

    $('#selectionChamp').val(selected_element.next().val());

  });
});

http://jsbin.com/ejunoz/2/edit

Pretty simple without jQuery too. This one will loop around to the first option once the last is reached:

function nextOpt() {
  var sel = document.getElementById('selectionChamp');
  var i = sel.selectedIndex;
  sel.options[++i%sel.options.length].selected = true;
}

window.onload = function() {
  document.getElementById('fieldNext').onclick = nextOpt;
}

Some test markup:

<button id="fieldNext">Select next</button>
<select id="selectionChamp">
 <option>0
 <option>1
 <option>2
</select>