<!DOCTYPE html>
<html>
<body>

First Name: <input type="text" id="myText" placeholder="Name">

<p>Click the button to change the placeholder text of the text field.</p>

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

<script>
function myFunction() {
    document.getElementById("myText").placeholder = "Type name here..";
}
</script>

</body>
</html>