jquery id存在

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>jQuery ID Example</title>
    <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
</head>
<body>
    <button id="myButton">Click me</button>
    <p id="myParagraph">Hello, World!</p>

    <script>
        $(document).ready(function() {
            // 通过 ID 选择元素
            var button = $("#myButton");
            var paragraph = $("#myParagraph");

            // 绑定事件处理函数
            button.click(function() {
                paragraph.text("Button clicked!");
            });
        });
    </script>
</body>
</html>

$(document).ready(function() {
    // 确保在此处执行 jQuery 代码
    var element = $("#nonExistentID");
    if (element.length === 0) {
        console.log("Element with ID 'nonExistentID' not found.");
    }
});