Выбранный вариант jQuery
$( "#myselect option:selected" ).val();
Difficult Duck
$( "#myselect option:selected" ).val();
$("select.country").change(function(){
var selectedCountry = $(this).children("option:selected").val();
alert("You have selected the country - " + selectedCountry);
});
$('select>option:eq(3)').prop('selected', true);
$('#mySelectElement option')[0].selected = true;