Managing API Versions with Request Headers or Path Parameters

class ApiClient {
  constructor(baseUrl, defaultVersion = 'v1') {
    this.baseUrl = baseUrl;
    this.defaultVersion = defaultVersion;
  }

  // Method 1: Versioning via path parameter
  async getByPath(resource, version = this.defaultVersion, options = {}) {
    const url = `${this.baseUrl}/${version}/${resource}`;
    try {
      const response = await fetch(url, options);
      if (!response.ok) {
        throw new Error(`API error (${version}): ${response.status} ${response.statusText}`);
      }
      return await response.json();
    } catch (error) {
      console.error(`Error fetching ${resource} with version ${version} (path):`, error);
      throw error;
    }
  }

  // Method 2: Versioning via custom header
  async getByHeader(resource, version = this.defaultVersion, options = {}) {
    const url = `${this.baseUrl}/${resource}`; // No version in path
    const headers = {
      'X-API-Version': version, // Custom header for versioning
      ...options.headers
    };
    try {
      const response = await fetch(url, { ...options, headers });
      if (!response.ok) {
        throw new Error(`API error (${version}): ${response.status} ${response.statusText}`);
      }
      return await response.json();
    } catch (error) {
      console.error(`Error fetching ${resource} with version ${version} (header):`, error);
      throw error;
    }
  }
}

// Example usage:
// const apiClient = new ApiClient('https://api.example.com');

// // Fetch data using default version (v1) via path
// apiClient.getByPath('users/1')
//   .then(data => console.log('User v1 (path):', data))
//   .catch(error => console.error(error));

// // Fetch data using v2 via path
// apiClient.getByPath('products', 'v2')
//   .then(data => console.log('Products v2 (path):', data))
//   .catch(error => console.error(error));

// // Fetch data using default version (v1) via header
// apiClient.getByHeader('settings')
//   .then(data => console.log('Settings v1 (header):', data))
//   .catch(error => console.error(error));

// // Fetch data using v3 via header
// apiClient.getByHeader('orders', 'v3')
//   .then(data => console.log('Orders v3 (header):', data))
//   .catch(error => console.error(error));