<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<div id="title">DOM</div>
<script>
document.getElementById("title").classList.add("h5");
var h1 = document.createElement("h1");
h1.innerHTML = "hellow";
h1.className = "h1";
document.getElementById("title").appendChild(h1);
if (document.getElementById("title").contains(h1)) {
alert("yes")
}
</script>
</body>
</html>