Authenticating API Requests with JWT Bearer Token

async function fetchAuthenticatedData(url, token, options = {}) {
  try {
    const headers = {
      ...options.headers, // Merge any existing headers
      'Authorization': `Bearer ${token}`
    };

    const response = await fetch(url, {
      ...options, // Merge any other fetch options (method, body, etc.)
      headers: headers
    });

    if (response.status === 401 || response.status === 403) {
      // Handle token expiration or invalid token
      console.error("Authentication failed or token expired. Please re-authenticate.");
      // Example: Redirect to login page or refresh token
      // window.location.href = '/login';
      throw new Error(`Authentication error! status: ${response.status}`);
    }

    if (!response.ok) {
      throw new Error(`HTTP error! status: ${response.status}`);
    }

    return await response.json();
  } catch (error) {
    console.error("Error in authenticated fetch:", error);
    throw error;
  }
}

// Example usage:
// const userToken = localStorage.getItem('jwtToken'); // Get token from storage
// if (userToken) {
//   fetchAuthenticatedData('https://api.example.com/user/profile', userToken)
//     .then(profileData => console.log('User Profile:', profileData))
//     .catch(error => console.error('Failed to fetch profile:', error));
// } else {
//   console.warn('No authentication token found. Please log in.');
//   // Redirect to login or show login prompt
// }