<!DOCTYPE html>
<html>
<body>
<p>Click the button to change the background color of all child elements of body.</p>
<button onclick="myFunction()">Try it</button>
<h2>I am a h2 element</h2>
<div>I am a div element</div>
<span>I am a span element</span>
<script>
function myFunction() {
var c = document.body.children;
var i;
for (i = 0; i < c.length; i++) {
c[i].style.backgroundColor = "red";
}
}
</script>
</body>
</html>