console 命令行工具 X clear

console

function insertAfter(referenceNode, newNode) {
    let parentNode = referenceNode.parentNode;
    if (parentNode.lastChild == newNode) {
        parentNode.appendChild(newNode);
    } else {
        let newNode_nextnode = referenceNode.nextSibling;
        parentNode.insertBefore(newNode, newNode_nextnode);
    }
}

let newNode = document.createElement('h1');
newNode.innerText = "真好";
insertAfter(document.getElementById('ans'), newNode);

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>lianxi</title>
    <script src="./1.js"></script>
</head>
<body>
    <div>
        <h1>欢迎访问本网页</h1>
    </div>
    <div>hello  haizei</div>
    <div id="ans">hello world</div>
    <div>hello hazei</div>
</body>

</html>