How do you display a JavaScript alert from PHP?

Question

I don't code in PHP, but I have this form which I pulled off the web and its working great:

What I would like to do is somehow add some code in here that can fire up a JS script, simple alert box, saying "Thank you form is submitted". After the form was received by this mailer.php file.

<?php
if(isset($_POST['submit'])) {

$to = "[email protected]";
$subject = "Form Tutorial";
$name_field = $_POST['name'];
$email_field = $_POST['email'];
$message = $_POST['message'];

$body = "From: $name_field\n E-Mail: $email_field\n Message:\n $message";

echo "Data has been submitted to $to!";
mail($to, $subject, $body);

} else {

echo "blarg!";

}
?>

Answer 1

instead of:

echo "Data has been submitted to $to!";

just

echo '<script type="text/javascript">alert("Data has been submitted to ' . $to . '");</script>';