在jquery ajax请求到php后，无法删除引导模式中选定的选择字段

在jqueryajax请求使用bootstrap模式之后，我希望将表单设置为空。 这是我用jqueryajax从modal服务器获取数据并发送给它的代码。 在切换模式之前，我使用val将字段设置为空，并使用prop取消选择、选择单选按钮和选择元素

Modal的HTML代码

<div id="addEmployeeModal" class="modal fade">
        <div class="modal-dialog">
            <div class="modal-content">
                <form id="AddUserForm">
                    <div class="modal-header">                      
                        <h4 class="modal-title">Add User</h4>
                        <button type="button" class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
                    </div>
                    <div class="modal-body">                    
                        <div class="form-group">
                            <label>First Name</label>
                            <input type="text" id="first_name" name="first_name" class="form-control" required>
                        </div>
                        <div class="form-group">
                            <label>Last Name</label>
                            <input type="text" id="last_name" name="last_name" class="form-control" required>
                        </div>
                        <div class="form-group">
                            <label>Email</label>
                            <input type="email" id="email" name="email" class="form-control" required>
                        </div>
                        <div class="form-group">
                            <label>Phone</label>
                            <input type="text" id="phone" name="phone" class="form-control" required>
                        </div>
                        <div class="form-group">
                            <center>
                                <label class="radio-inline">
                                    <input type="radio" id="gender" name="gender" value="1" required>Male
                                </label>
                                <label class="radio-inline">
                                    <input type="radio" id="gender" name="gender" value="0" required>Female
                                </label>
                            </center>
                            <!--<input type="radio" id="gender" name="gender" class="form-control" required>
                            <input type="radio" id="gender" name="gender" class="form-control" required>-->
                        </div>
                        <div class="form-group">
                            <label>Type</label>
                            <select class="selectpicker form-control show-tick" data-live-search="true" title="Select Please" id="role" name="role">
                                <option value="student">Student</option>
                                <option value="teacher">Teacher</option>
                                <option value="clerk">Clerk</option>
                                <option value="lab_staff">Lab Staff</option>
                                <option value="admin">Admin</option>
                            </select>
<!--                            <textarea class="form-control" required></textarea>-->
                        </div>
                    </div>
                    <div class="modal-footer">
                        <input type="button" class="btn btn-default" data-dismiss="modal" value="Cancel">
                        <input type="submit" id="InsertSubmit" class="btn btn-success" value="Add">
                    </div>
                </form>
            </div>
        </div>
    </div>

JQuery代码

                   <script>
    $( document ) . ready( function () {
        $( "#AddUserForm" ) . on( 'submit', function () {
            var first_name = $( "#first_name" ) . val();
            var last_name = $( "#last_name" ) . val();
            var email = $( "#email" ) . val();
            var phone = $( "#phone" ) . val();
            var gender = $( "#gender" ) . val();
            var role = $( "#role" ) . val();
            // Returns successful data submission message when the entered information is stored in database.
            var dataString = 'first_name=' + first_name + '&last_name=' + last_name + '&email=' + email + '&phone=' + phone + '&gender=' + gender + '&role=' + role;

            // AJAX Code To Submit Form.
            $ . ajax( {
                type: "POST",
                url: "add_user.php",
                data: dataString,
                cache: false,
                success: function ( result ) {
                    $("#addEmployeeModal #first_name").val('');
                    $("#addEmployeeModal #last_name").val('');
                    $("#addEmployeeModal #email").val('');
                    $("#addEmployeeModal #phone").val('');
                    $("#addEmployeeModal #gender").prop('checked', false);
                    $("#addEmployeeModal #role option").prop('selected', false);
                    $( '#addEmployeeModal' ) . modal( 'toggle' );
                    toastr . options = {
                        "closeButton": true,
                        "debug": false,
                        "newestOnTop": false,
                        "progressBar": false,
                        "positionClass": "toast-top-right",
                        "preventDuplicates": false,
                        "onclick": null,
                        "showDuration": "300",
                        "hideDuration": "1000",
                        "timeOut": "5000",
                        "extendedTimeOut": "1000",
                        "showEasing": "swing",
                        "hideEasing": "linear",
                        "showMethod": "fadeIn",
                        "hideMethod": "fadeOut"
                    }
                    toastr[ "success" ]( "User Added" );

                }
            } );

            return false;
        } );
    } );
</script>

现在一切正常，但是id=role的选定字段没有被清除。

---

现在该怎么办。

发布更多代码？请参阅：同时提及您使用的引导程序的版本。3.3.7还是4.0？确保你的选择有一个“空”选项，你可以选择。我编辑了这篇文章，请现在查看。