const URL_CHAT_REGISTRATION = `http://localhost:8080/api/chat/register`; interface UserRegistrationResponse { id: string; accessToken: string; displayName: string; } class UserService { registerUser(username: string): Promise { const options = { method: 'POST', headers: { 'Content-Type': 'application/json', }, body: JSON.stringify({ displayName: username }), }; try { const response = await fetch(URL_CHAT_REGISTRATION, options); const result = await response.json(); return result; } catch (e) { console.error(e); } return null; } }