I am making a basic login webpage for class project. I want to check the password and confirm password should match. If they are not same then it should give an alert message. But here I don't get that error message.

<!DOCTYPE html> <html> <head> <title>Login Here!!</title> <link rel="icon" type="image/ico" href="pics/down.jpg" /> <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous"> <link href="https://fonts.googleapis.com/css?family=Roboto+Slab" rel="stylesheet"> </head> <style> form{ border: 2px solid grey; border-radius: 5%; padding: 20px 50px; margin-top: 5%; background-color:#f9f6fa; }

img{

    text-align: center;
}
 input[type="submit"]{
    margin-left: 35%;
    border-radius: 75%;
    padding: 2% 10% ;
 }
</style>
<body class="jumbotron container-fluid">
     <header style="text-align: center;"><h1 style="font-family:'Roboto Slab', serif;">Login Here!! </h1></header>
     <main class="row">
        <div class="col-xs-4"></div>
        <div class="col-xs-4">
            <form id="login" action = '' target="_blank">
                <div id="img">
                    <img src="pics/image.png" width="100px" height="100px">
                </div>
                <div class="form-group">
                    <label for="name">Username: </label>
                    <input type="text" id="name"  class="form-control" name="name" placeholder="Enter username here...">
                </div>
                <div class="form-group">
                    <label for="paswd">Password :</label>
                    <input type="password" id="paswd" name="paswd" class= "form-control">
                </div>
                <div class="form-group">
                    <label for="repeat-paswd">Confirm Password :</label>
                    <input type="password" id="confrm_paswd" name="confrm_paswd" class= "form-control">
                </div>
                <div class="form-group">
                    <input type="checkbox" name="rembr_me" checked>&nbspRemember Me
                </div>
                <input type="submit" value="Submit" class="btn btn-primary"> 
            </form>
        </div>
        <p id="thank_you" hidden>You are now signing in</p>
     </main>
     <script>
     let form = document.querySelector('#login');
     let uname = document.getElementById('name').value;
     let passwd = document.getElementById('paswd').value;
     let conf_passwd = document.getElementById('confrm_paswd').value;
     if(passwd != conf_passwd)
             alert('Password does not match');
     form.onsubmit = function(){
        if(uname == '' && (passwd == '' && conf_passwd == '' )) 
             alert('One or more fields are empty');
     }
     </script>
</body>

</html>