<!DOCTYPE html>
<html>
<body>
Name: <input type="text" id="myText">
<p>Click the button to set the text field to read-only.</p>
<p><strong>Tip:</strong> To see the effect, try to type something in the text field before and after clicking the button.</p>
<button onclick="myFunction()">Try it</button>
<script>
function myFunction() {
document.getElementById("myText").readOnly = true;
}
</script>
</body>
</html>