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