js没有获取的img元素出错


<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>音乐播放器</title>
        <link rel="stylesheet" href="css/style.css">
        <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.15.3/css/all.min.css" />
        <script src="https://kit.fontawesome.com/a062562745.js" crossorigin="anonymous"></script>
        <script src="js/data.js"></script>
        <script src="js/app.js"></script>
    </head>
    <body>
        <audio src="" id="audio=source"></audio>
        <!-- home section -->
        <section class="home-section active">
            <div class="carousel">
                <img src="assets/images/cover-1.png" class="active" alt="" />
                <img src="assets/images/cover-5.png" alt="" />
                <img src="assets/images/cover-6.png" alt="" />
                <img src="assets/images/cover-7.png" alt="" />
                <img src="assets/images/cover-10.png" alt="" />
            </div>
        </section>
        
    </body>
</html>

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>音乐播放器</title>
        <link rel="stylesheet" href="css/style.css">
        <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.15.3/css/all.min.css" />
        <script src="https://kit.fontawesome.com/a062562745.js" crossorigin="anonymous"></script>
        <script src="js/data.js"></script>
        <script src="js/app.js"></script>
    </head>
    <body>
        <audio src="" id="audio=source"></audio>
        <!-- home section -->
        <section class="home-section active">
            <div class="carousel">
                <img src="assets/images/cover-1.png" class="active" alt="" />
                <img src="assets/images/cover-5.png" alt="" />
                <img src="assets/images/cover-6.png" alt="" />
                <img src="assets/images/cover-7.png" alt="" />
                <img src="assets/images/cover-10.png" alt="" />
            </div>
        </section>
        
    </body>
</html>

img

        <script src="js/data.js"></script>
        <script src="js/app.js"></script>

不要放在标签里，一般在最下面

如果你的js文件里面涉及到在加载过程中去操作DOM的话，那你需要放在body里的最后面去引入，放在header容易导致在操作DOM时元素还没加载而导致保错，因为js的加载会阻塞后面html的解析与渲染