ลองตัวเอง - JavaScript Reference link

<!DOCTYPE html>
<html>
<head>
</head>
<body>

<p>Click the button to create a LINK element.</p>

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

<script>
function myFunction() {
   var x = document.createElement("LINK");
   x.setAttribute("rel", "stylesheet");
   x.setAttribute("type", "text/css");
   x.setAttribute("href", "styles.css");
   document.head.appendChild(x);
}
</script>

</body>
</html>