views/login.erb
<!doctype html>
<html lang="ja">
<head>
<meta charset="utf-8">
<title>OpenYo</title>
<script src="//ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
</head>
<body>
<h1>login:</h1>
<span id="head"></span>
<p>
id: <input type="text" id="id" size="20" /><br />
pass: <input type="password" id="pass" /><br />
<input type="submit" id="auth" value="認証" /><br />
<span id="authMsg"></span><br />
</p>
<input type="submit" id="logout" value="Logout" /><br />
<span id="logoutMsg"></span>
<h2>Sign up</h2>
Or you are not signed up yet?<br />
Sign up now from <a href="/signup/">HERE!</a>
</body>
<script src="/js/login.js"></script>
</html>