<!DOCTYPE html>
<html>
<head>
<link id="myLink" href="domoarigato.htm" hreflang="ja">
</head>
<body>
<p>Click the button to change the language code of the linked document.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
document.getElementById("myLink").hreflang = "en-us";
document.getElementById("demo").innerHTML = "The language code was changed from 'ja' to 'en-us'.";
}
</script>
</body>
</html>