So it works backwards.
<input type=”text” id=”username” disabled=”disabled” /><br />
<input type=”password” id=”password” disabled=”disabled” /><br />
<input type=”submit” id=”login” value=”login” disabled=”disabled” />
If you have a form that is disabled, then reenable it by setting disabled property back to false.
var login = document.getElementById(‘login’);
Clean up any opacity or other styling/functions you have set in the case of a failure.