我正在为我的网站创建一个个人信息系统。为此，我想实时显示和更新每个聊天中的新消息数量，类似于下面屏幕截图中显示的红色“框”：

目前，消息计数没有写在提供的div中，我不知道为什么。
下面是相关的HTML代码：

<div class="chat_body"> 
    <a href="index.php?section=pn&mode=loadConversation&ConversationID=<?php echo $conversation['id']; ?>">
        <div class="user" id='<?php echo $i ?>' data-user-id='<?php echo $user_id?>' data-conv-id='<?php echo $conversation['id'] ?>'>
            // Displaying the name, etc...
        <?php                   
            echo "<div class='rightCountUnreadMessages'>";
                /* Showing the actual counter */
                echo '<div class="badge" id="badge-'.$i.'"></div>';
            echo "</div>";
        ?>
        </div>
    </a>
</div>

jQuery函数，它应该确定每500ms新消息的数量：

jQuery(document).ready(function() {
    //jQuery(setInterval(function() {
        friends_count = document.getElementsByClassName("user").length;
        for(var i=1; i < friends_count+1; i++) {
            el = document.getElementById(i);
            conv_id = el.getAttribute("data-conv-id");
            user_id = el.getAttribute("data-user-id");
            test = i;

            jQuery.post('./Bauteile/Accounts/loadCounts/loadPNCount.php', {user_id_loadPN: user_id, conv_id: conv_id}, function(result){
                console.log(result);
                if(result > 99) result = "99+";

                if(result > 0 || result == "99+") {
                    document.getElementById("badge-"+test).innerHTML = result;
                }
            })
        }
    //}, 500));
});

并在Javascript中请求的文档中有以下内容：

<?php
    $conv_id = $_POST['conv_id'];
    $from_id = $_POST['user_id_loadPN'];

    echo (int)mysql_result(mysql_query("SELECT COUNT(*) FROM `messages` WHERE `group_id` = $chat_id AND `from_id` = $from_id AND `read_on` is NULL"), 0);
?>