Alert Box for webpage. Javascript/HTML

I’m working on an assignment for school and it’s asking me to create an alert for two email addresses being different. What I have works as far as giving an alert when the two emails are different, except that it gives an alert in any other case as well. How do I fix this? Here’s what I got:

        <form method="POST">
            <p>
               <label for="email">Email Address:</label>
               <input type="text" name="email" id="email">
            </p>
            <p>
               <label for="confirmation">Confirm Email:</label>
               <input type="text" name="confirmation" id="confirmation">
            </p>
            <p>
                <textarea placeholder="Ask question here" id="textarea"></textarea>
            </p>
         </form>
         
         <button onclick="alertBox()">Submit</button>

         <script>
         function alertBox() {
            let email = document.getElementById("email");
            let confirmation = document.getElementById("confirmation");
            if (email != confirmation) {
                alert("Email addresses do not match. Please try again.");
            }
         }
         </script> ```

The assignment says to create a "submit" button and that the form isn't supposed to be submitted to a server, hence no action attribute in the form element and a button instead of input type submit. Any help is appreciated.