<html>
<head>
<script> function replaceText(){
var myTextNode = document.createTextNode("Text was replaced");
var newTN = replaceMe.firstChild.replaceNode(myTextNode);
}
</script>
</head>
<p id="replaceMe">This is some text that will be replaced</p>
<button onclick="replaceText();">Replace text</button>
</body>
</html>