index.php

<!DOCTYPE html>
<html>
<head>
	<title></title>
	<script src="./jquery.js"></script>
	<script type="text/javascript" src="./jquery.base64.min.js"></script>
</head>
<body>

	<form method="POST" class="login-form" action="">
		<input type="text" name="email">
		<br>
		<input type="password" name="password">
		<br>
		<button type="submit" class="submit" name="submit">Login</button>
	</form>

	<?php
		if (isset($_POST) && !empty($_POST)) {
			echo '<pre>';
			print_r($_POST);
			echo '</pre>';
			echo 'Encrypted Password- ' . $_POST['password'];
			echo '<br/>';
			echo 'Password- ' . base64_decode($_POST['password']);
		}
	?>
	<script type="text/javascript">
		$(document).ready(function() {
			$('button.submit').on('click', function(e) {
				var form = $(this).parents('form');
				var passwordField = $(form).find('input[type="password"]');
				var password = $(passwordField).val();
				var encPassword = $.base64.encode(password);
				$(passwordField).val(encPassword);
			});
		});
	</script>
</body>
</html>