parentNode

js/script.js

function funMake() {
var str = document.getElementById('p1').parentNode.nodeName;
document.getElementById('d2').innerHTML = '<h3>' + str + '</h3>';
}

function funMake() {
var str = document.getElementById('p1').parentNode.nodeName;
document.getElementById('d2').innerHTML = '<h3>' + str + '</h3>';
}

index.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
<script src="js/script.js"></script>
</head>
<body>
<div>
<p id="p1">Hello World!</p>
<h4>Привет Мир!</h4>
<div>To be or not to be?</div>
</div>
<div id="d2"></div>
<script>
funMake();
</script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
<script src="js/script.js"></script>
</head>
<body>
<div>
<p id="p1">Hello World!</p>
<h4>Привет Мир!</h4>
<div>To be or not to be?</div>
</div>
<div id="d2"></div>
<script>
funMake();
</script>
</body>
</html>