Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<body>

<p>Click the button to create a FORM and an INPUT element.</p>

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

<script>
function myFunction() {
    var x = document.createElement("FORM");
    x.setAttribute("id", "myForm");
    document.body.appendChild(x);

    var y = document.createElement("INPUT");
    y.setAttribute("type", "text");
    y.setAttribute("value", "Donald");
    document.getElementById("myForm").appendChild(y);
}
</script>

</body>
</html>