JSFiddle - React, Tailwind, and code Playground

HTML

<input class="login-inpt" runat="server" name="loginName" type="text" value="User Name" />

JavaScript

$('.login-inpt').focus(function() {
   $(this).val('');
});
$('.login-inpt').focusout(function() {
   $(this).val('User Name');
});