<!DOCTYPE html>
<html>
<body>
<head>
<meta name="description" content="Free Web tutorials">
<meta name="keywords" content="HTML5,CSS,JavaScript">
<meta name="author" content="John Doe">
</head>
<p>Click the button to change the value of the content attribute of the third meta element (index 2) in head.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
document.getElementsByTagName("META")[2].content = "Bill Mosley";
document.getElementById("demo").innerHTML = "The content in meta name 'author' was changed from 'John Doe' to 'Bill Mosley'.";
}
</script>
</body>
</html>