CustomerChat.js

//frontend/src/CustomerChat.js:6
useEffect(() => {
    const handleUnload = (event) => {
        event.preventDefault();
        fetch('http://localhost:8080/email-transcript', {
            method: 'POST',
            headers: {
                'Accept': 'application/json',
                'Content-Type': 'application/json'
            },
            body: JSON.stringify({
                messages: channel.state.messages,
                firstName: firstName,
                lastName: lastName,
                email: email,
                createdAt: channel.data.config.created_at
            })
        });
        event.returnValue = '';
    };

    window.addEventListener('beforeunload', handleUnload);

    return () => {
        window.removeEventListener('beforeunload', handleUnload);
    };
}, [channel, firstName, lastName, email]
);