console
function insertAfter(referenceNode, newNode) {
var parentNode = referenceNode.parentNode;
if (parentNode.lastChild == newNode) {
parentNode.appendChild(newNode);
} else {
var newNode_nextnode = referenceNode.nextSibling;
parentNode.insertBefore(newNode, newNode_nextnode);
}
}
var newNode = document.createElement('p');
newNode.innerText = "script";
insertAfter(document.getElementById('hello'), newNode);
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>lianxi</title>
<script src="./node.js"></script>
</head>
<body>
<div id = "hello">hello world</div>
<div>sss</div>
<div>aaa</div>
</body>
</html>