Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<body><p>This is the first p element in body.</p>

<p>Click the button to change the HTML content of the body element's first child node (index 0).</p>

<button onclick="myFunction()">Try it</button>

<script>
function myFunction() {
    document.body.childNodes[0].innerHTML = "Changed!";
}
</script>

</body>
</html>