<html>
<head><style>body {min-height: 300px;} input { font-size: 16px; } textarea { font-size: 16px; } </style></head>
<body>
<input id="usernameInput" type="text" placeholder="Username">
<button onclick="register()">Register</button>
<p id="message"></p>
<script>var username = document.getElementById("usernameInput").value;</script>
</body>
</html>]]>Make sure to assemble .value
.