<!DOCTYPE html>
<html>
<head></head>
<body>
<div id="div-id">
<p id="p-id">p-id tag</p>
</div>
<script>
var parent = document.getElementById("div-id");
var childp = document.getElementById("p-id");
var newp = document.createElement("p");
var nodetext = document.createTextNode("new p");
newp.appendChild(nodetext);
parent.replaceChild(newp, childp);
/*
run:
<p>new p</p> will replace: <p id="p-id">p-id tag</p>
*/
</script>
</body>
</html>