Javascript 我能'；我不明白弹出窗口为何消失&；出现'；这是一个错误或当它发送

我为注册一个网站写了一个弹出窗口。它可以正常工作，除了一个方面-当用户未能提供所有必要的信息，弹出窗口将消失，但随后重新出现错误消息。同样，如果用户提供所有信息并单击“发送”，则消息将成功发送，但弹出窗口消失，然后再次出现成功消息。当用户单击“关闭”时，弹出窗口将关闭并保持不变

我一直在看代码，我就是不知道为什么它消失了，然后又出现了。我希望它停留在那里，显示错误消息或成功消息，然后只在用户单击“关闭”时消失

这是你可以在行动中看到的

我感谢所有的建议！谢谢

HTML PHP

---

表单的提交请求基本上会重新加载页面，从而再次启动window.onload功能

当您单击弹出窗口中的按钮时，您会将请求发送回服务器，从而重新加载整个页面。如果不想重新加载页面，则需要使用Ajax。

<?php include $_SERVER['DOCUMENT_ROOT']. '/php/signup-popup.php'; ?>
        <div id="pop-wrapper">
    <!-- Popup Div Starts Here -->
    <div id="popupContact">
    <!-- Contact Us Form -->
                <form action="#" id="form" method="post" name="form">
        <h2 id="popup-h2">Join the Civil War Digital Digest</h2>
        <hr>
        <input id="name" name="name" placeholder="Name" type="text" value="<?php echo htmlspecialchars($_POST['name']);?>">
        <input id="email" name="email" placeholder="Email" type="text" value="<?php echo htmlspecialchars($_POST['email']);?>">
        <textarea id="msg" name="message" placeholder="Message"><?php echo htmlspecialchars($_POST['message']);?></textarea>
                    <?php echo "<p id='error-message' class='text-danger'>$errError</p>";?>
                    <?php echo $result; ?>
                    <button id="submit" name="submit" type="submit" value="Send">Send</button>
        <br>
        <button onclick="hide()" id="close">Close</button>
                </form>
    </div>
    <!-- Popup Div Ends Here -->
        </div>

function show() {
    if(sessionStorage.getItem("close") == null){
        document.getElementById('pop-wrapper').style.display = "block";
     }
     else {
        document.getElementById('pop-wrapper').style.display = "none";
     }          
 }

    function hide(){
        sessionStorage.setItem("close", 1);
        document.getElementById('pop-wrapper').style.display = "none";
    }


    window.onload=function(){
        setTimeout(function(){
            show();
        }, 500);
    }

<?php
    if (isset($_POST["submit"])) {
        $name = $_POST['name'];
        $email = $_POST['email'];
        $message = $_POST['message'];
        $from = 'Civil War Digital Digest Popup Form'; 
        $to = 'kennethpavia@gmail.com'; 
        $subject = 'Message from CWDD Popup Form ';

        $body ="From:\n Name: $name\n E-Mail: $email\n Message:\n $message";

        // Check for errors
        if (!$_POST['name'] || !$_POST['email'] || !$_POST['message']) {
            $errError = 'Some information is missing. Unable to send.';
        }

        // If there are no errors, send the email
                if (!$errError) {
                    if (mail ($to, $subject, $body, $from)) {
                        $result='<div class="alert alert-success">Message sent. Thank you for contacting the CWDD.</div>';
                    } else {
                        $result='<div class="alert alert-danger">Sorry, there was an error sending your message. Please try again.</div>';
                    }
                }

    }
?>

/* popup header color #394650 */
        /*font IM Fell DW Pica */

        /*----------------------------------------------
        CSS settings for HTML div Exact Center
        ------------------------------------------------*/
        #pop-wrapper {
            width:100%;
            height:100%;
            opacity:.99;
            top:0;
            left:0;
            display:none;
            position:fixed;
            background-color:#313131;
            overflow:auto;
        }

            div #popupContact {
                position:absolute;
                left:50%;
                top:17%;
                margin-left:-202px;
                font-family:'IM Fell DW Pica', serif;
            }

            form {
                                width: 450px;
                                height: 680px;
                /*max-width:300px;
                min-width:250px;*/
                padding:10px 50px;
                border:2px solid gray;
                border-radius:10px;
                font-family:raleway;
                background-color:#fff;
            }

            #error-message {
                /*margin-top:30px;*/
                                font-size: 18px !important;
            }

            #popup-h2 {
                background-color:#394650;
                padding:20px 35px;
                margin:-10px -50px;
                text-align:center;
                border-radius:10px 10px 0 0;
                color: #fff;
            }
            hr {
                margin:10px -50px;
                border:0;
                border-top:1px solid #ccc;
            }
            input[type=text] {
                width:82%;
                padding:10px;
                margin-top:30px;
                border:1px solid #ccc;
                padding-left:40px;
                font-size:16px;
                font-family: raleway;
            }
            #name {
                background-repeat:no-repeat;
                background-position:5px 7px;
            }
            #email {
                background-repeat:no-repeat;
                background-position:5px 7px;
            }
            textarea {
                background-repeat:no-repeat;
                background-position:5px 7px;
                width:82%;
                height:95px;
                padding:10px;
                resize:none;
                margin-top:30px;
                border:1px solid #ccc;
                padding-left:40px;
                font-size:16px;
                font-family:raleway;
                margin-bottom:30px;
            }
            #submit, #close {
                text-decoration:none;
                width:100%;
                text-align:center;
                display:block;
                background-color:#394650;
                color:#fff;
                border:1px solid #fff;
                padding:10px 0;
                font-size:20px;
                cursor:pointer;
                border-radius:5px;
            }
            span {
                color:red;
                font-weight:700;
            }
            button {
                width:10%;
                height:45px;
                border-radius:3px;
                background-color:#cd853f;
                color:#fff;
                font-family:'IM Fell DW Pica', serif;
                font-size:18px;
                cursor:pointer;
            }