Avoid same option selected multiple times using jquery

Answer 1

Try with attribute selector in jquery

$('[id ^= "table"] tr').find('select').change(function() {
    if ($(this).closest('table').find('option[value=' + $(this).val() + ']:selected').length > 1) {
        alert('option is already selected');
        $(this).val($(this).find("option:first").val());
    }
});

Fiddle