How do I require the examinee to fill in the prompt before exiting the page? [duplicate]

So I have an examination page, and the user cannot leave until it’s over. They can only leave if they know the password or examination ended. However, I don’t know how to do that. I have tried to use Prompt and Do While, but I get nothing. No errors or popups

Here’s what i have tried so far

window.onbeforeunload = (event) => {
    prompt("Enter password before you leave!");
        let confirm;
        while (true) {
            confirm= (prompt("Enter password before you leave!"));
    
            if (confirm != "44344")
                return confirm;
            alert("You can't leave while the examination is still ongoing.");
            event.preventDefault();
        }
}

I’m expecting to loop a prompt until the user gets the correct password or they cancel the prompt.

I have seen others post in stackoverflow but it does only confirm the user if they want to leave or not.