<!DOCTYPE html>
<html>
<body>
E-mail: <input type="email" id="myEmail" value="johndoe@example.com">
<p>Click the button to change the email address of the email field.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
document.getElementById("myEmail").value = "steve@w3schools.com";
}
</script>
</body>
</html>