className.remove 不工作。单击按钮时尝试删除活动

Question

我正在尝试创建一个删除活动功能，但它不会注册，并且我的控制台上出现错误：

Uncaught TypeError: Cannot read properties of undefined (reading 'remove')

除了document.queryselector 或document.queryselectorAll 之外，还有什么其他方法可以添加删除功能，因为我也尝试过它们，但仍然无法正常工作。我已经添加了下面的所有代码。

JavaScript

var container = document.getElementById("btn-tab");
        var current = container.getElementsByClassName("active");
        var press = document.getElementById(this.btn); 
        current.className.remove("active");
        press.className += " active";

HTML

<div id="btn-tab" class="tabs">
                        <button id="tabnews" class="tablinks active" onclick="openFeed(this)">LATEST NEWS</button>
                        <button id="tabevents" class="tablinks" onclick="openFeed(this)">EVENTS</button>
                        <button id="tabgroup" class="tablinks" onclick="openFeed(this)">GROUP</button>
                    </div>
<div id="tabs-feed">
                test123
            </div>
    

主题功能

function js_swappost() {
    //swap_post_type is a local name for the ajax call and is onlyused in her
    wp_enqueue_script ("swap_post_type", get_stylesheet_directory_uri() . "/assets/js/ajax.js", array('jquery')) ; 
    //ajax_var is declaring a variable that is available in the client script for accessing data about the Ajax handler
    //nonce is a security featur to prevent injection of Ajax calls
    wp_localize_script('swap_post_type', 'ajax_var', array('ajaxurl' => admin_url('admin-ajax.php'), 'nonce' => wp_create_nonce('swapposttype'))) ;
} 
add_action("wp_enqueue_scripts", "js_swappost") ;

//This is the function to be called when the  Ajax call is made
function swap_post_ajax() {
    //Get the post data type to be shown, defaults to Latest News
    $type = (isset($_POST["postType"])) ? $_POST["postType"] : 'latestNews' ;
    //Get the nonce security code, default to 0
    $nonce =(isset($_POST["nonce"])) ? $_POST["nonce"] : 0 ;
    
    //Check that the security code is correct
    if (wp_verify_nonce($nonce, 'swapposttype')) {
        if ($_POST == "latestNews"){
//          latestnewsFeed() ;
            echo '<p>test</p>';
        }
        
        else{
            if ($_POST == "events")
//              eventsFeed();
            echo '<p>test1</p>';
        
        else {
//          groupFeed();
            echo '<p>Why is this not working?</p>';
            }
        }
    }
    else {
        echo 'Security Alert' ;
    }
    wp_die() ; //Needed to stop WordPress processing normally
}
//This is the code that actually registers the Ajax call wp_ajax is need with the element of 'swap_post_ajax' used to map to the function declared above
add_action('wp_ajax_nopriv_swap_post_ajax', 'swap_post_ajax') ; //Register the event for logged out users
add_action('wp_ajax_swap_post_ajax', 'swap_post_ajax') ; //Register the event for logged in users

CSS

button#tabnews {
    position: relative;
    bottom: 130px;
    font-size: 40px;
    display: flex;
    flex-direction: column;
    flex-wrap: wrap;
    align-content: center;
    justify-content: space-between;
    align-items: flex-start;
    font-family: highvoltage-rough;
    background: #17CBC5;
    width: 50%;
    padding: 20px;
    color: white;
    border-radius: 0px;
    margin: 5px;
    font-style: normal;
    font-weight: 400;
}
    button#tabevents {
    position: relative;
    bottom: 130px;
    font-size: 40px;
    display: flex;
    flex-direction: column;
    flex-wrap: wrap;
    align-content: center;
    justify-content: space-between;
    align-items: flex-start;
    font-family: highvoltage-rough;
    background: #17CBC5;
    width: 50%;
    padding: 20px;
    color: white;
    border-radius: 0px;
    margin: 5px;
    font-style: normal;
    font-weight: 400;
}
    
    button#tabgroup {
    position: relative;
    bottom: 130px;
    font-size: 40px;
    display: flex;
    flex-direction: column;
    flex-wrap: wrap;
    align-content: center;
    justify-content: space-between;
    align-items: flex-start;
    font-family: highvoltage-rough;
    background: #17CBC5;
    width: 50%;
    padding: 20px;
    color: white;
    border-radius: 0px;
    margin: 5px;
    font-style: normal;
    font-weight: 400;
}
    
    

@media screen and (max-width: 768px) {
.tablinks {
    display: flex;
    justify-content: space-between;
    margin-left: 5px;
    margin-right: 5px;
    margin-top: 20px;
    max-width: 50%;
    text-align: left;
    height: 70px;
}
}

    .active{
        color: blue;
    }
    
.tablinks:hover {
  background-color: #17cbc5;
  color: white;
  opacity: 1;
}

.tablinks .active {
  background-color: #17cbc5;
}
    
.tablinks{
    text-align: center;
    position: relative;
    margin-top: 0;
    margin-bottom: -135px;
    top: -127px;
}

@media (max-width: 959px) {
    .tablinks {
    text-align: center;
    position: relative;
    margin-top: 0;
    margin-bottom: -160px;
    top: -158px;
}
}

@media (max-width: 650px) {
.tablinks {
    text-align: center;
    position: relative;
    margin-top: 0;
    margin-bottom: -170px;
    top: -257px;
}
}

@media (max-width: 425px) {
.tablinks {
    text-align: center;
    position: relative;
    margin-top: 0;
    margin-bottom: -74px;
    top: -111px;
}
}

@media (max-width: 375px) {
    .tablinks {
    text-align: center;
    position: relative;
    margin-top: 0;
    margin-bottom: -88px;
    top: -113px;
}
}

@media (max-width: 366px) {
    .tablinks {
    text-align: center;
    position: relative;
    margin-top: 0;
    margin-bottom: -151px;
    top: -166px;
}
}

Answer 1

您的问题是您试图将“getElementsByClassName”放到另一个元素上。这行不通。您可以通过以下方式选择具有该类的容器的所有子项：

var current = document.querySelectorAll('#btntab > .active');

因此，您的最终代码如下所示：

var container = document.getElementById('btn-tab');
var current = document.querySelectorAll('#btntab > .active');
var press = document.getElementById('this.btn');
current.className.remove('active');
press.classList.add('active');