When you select the button it will change the background color and let you know about it.
The background of this page is white
<!DOCTYPE html>
<html>
<head>
<script src="myscripts.js"></script>
<title> Javascript example </title>
</head>
<body>
<h1> Javascript Example 1: Change background color </h1>
<button type="button" onclick="yellow()"> change background to yellow </button>
<p aria-live="assertive" id="color"> The background of this page is white </p>
</body>
</html>
function yellow() {
document.body.style.backgroundColor = "yellow" ;
document.getElementById("color").innerHTML = "background is now yellow!" ;
}