ลองตัวเอง - JavaScript Reference textarea

<!DOCTYPE html>
<html>
<body>

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

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

<script>
function myFunction() {
   var x = document.createElement("TEXTAREA");
   var t = document.createTextNode("At w3schools.com you will learn how to make a website.");
   x.appendChild(t);
   document.body.appendChild(x);
}
</script>

</body>
</html>