使用.hide()jquery后,Div重新出现

$(function() {
    $('.btn-save').click(function(e) {
        e.preventDefault();

        var name = $('#name').val();
        var surname = $('#surname').val();

        if (name === "" && surname === "") {
            alert("Please, enter your details!");
            $("#UQ").hide();
        }
        else if(name !== "" && surname === "") {
            alert("Please, enter your Surname");
            $("#UQ").hide();
        }
        else if(name === "" && surname !== "") {
            alert("Please, enter your Name");
            $("#UQ").hide();
        }
        else {
            $.post("saveDetails.php", { 
                name: name,
                surname: surname 
            });
            $("#detailsDiv").hide();
            $("#UQ").show();
            alert('You have been successfully registered!');
        }   
    });
});