JSFiddle - React, Tailwind, and code Playground

HTML

<title></title>
<body>

<div class="container">
    <input name="udid" id="udid" type="text" value="dd" size="50">
    <input type="button" value="Get User Name(udid)" onclick="getUserName(document.getElementById('udid'));">
    <div>
    </div>
</div>

</body>
</html>

JavaScript

function getUserName(id){
    alert(id.value);
}