O que tem de errado no seguinte código, collapse e nem dropdown funciona.
<!doctype html> <html lang="en"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no"> <meta name="description" content=""> <meta name="author" content=""> <link rel="icon" href="favicon.ico"> <title> </title> <!-- Bootstrap core CSS --> <link href="css/bootstrap.min.css" rel="stylesheet"> <!-- Custom styles for this template --> <link href="css/signin.css" rel="stylesheet"> <script type="text/javascript"> $ (".dropdown-toggle").dropdown(); </script> </head> <body class="text-center"> <form class="form-signin bg-white rounded box-shadow"> <img class="mb-4" src="https://getbootstrap.com/assets/brand/bootstrap-solid.svg" alt="" width="72" height="72"> <label for="inputEmail" class="sr-only">Usuário</label> <input type="email" id="inputEmail" class="form-control" placeholder="Username" required autofocus> <label for="inputEmail" class="sr-only">Idade</label> <input type="date" id="inputEmail" class="form-control" name="bday" max="1979-12-31"required autofocus> <div class="btn-group"> <button type="button" class="btn btn-secondary dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false"> Right-aligned menu </button> <div class="dropdown-menu dropdown-menu-right"> <button class="dropdown-item" type="button">Action</button> <button class="dropdown-item" type="button">Another action</button> <button class="dropdown-item" type="button">Something else here</button> </div> </div> <label for="inputPassword" class="sr-only">Estado</label> <input type="text" id="inputEmail" class="form-control" placeholder="Country" required> <label for="inputPassword" class="sr-only">Cidade</label> <input type="text" id="inputPassword" class="form-control" placeholder="City/UF" required> <button class="btn btn-lg btn-block" type="submit">Registrar-se</button> <p class="mt-5 mb-3 text-muted">© 2017-2018</p> </form> <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script> <script src="js/bootstrap.min.js"></script> </body> </html> 
