jump input

    var dayInput = $('input[name=day]');
    var monthInput = $('input[name=month]');
    var yearInput = $('input[name=year]');

    $(document).on('keyup', dayInput, monthInput, yearInput, function(e){
        if (dayInput.val().length == 2){
            monthInput.focus();
        }
        if (monthInput.val().length == 2){
            yearInput.focus();
        }
        if (yearInput.val().length == 4){
            $('.js-dob').focus();
        }
    });