javascript - 使用 jQuery 实现个人消息系统的实时消息计数

Question

我正在为我的网站创建个人消息系统。为此，我想实时显示和更新每个聊天中的新消息数量，类似于以下屏幕截图中显示的红色“框”:

目前，消息计数未写入提供的 div 中，我不确定原因。

以下是相关的 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，应确定每 500 毫秒新消息的数量:

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));
});

在 Javascript 中请求的文档具有以下内容:

<?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);
?>

Answer 1

问题是你的循环中有一些异步的东西。为了解决这个问题，你需要一个闭包。您需要将 for 循环的内容包装在一个以 i 作为参数的函数中，然后在循环中调用该函数。

所以尝试这样的操作:

function doClosure(i) {
    var 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);
        console.log(test);

        if(result > 99) {
            result = "99+";
        }

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

for (var i = 1; i < document.getElementsByClassName("user").length+1; i++) {
    doClosure(i);
}