Best Practices for Working with Axios in Node.js

As a Node.js developer, making HTTP requests is a fundamental part of building modern applications. Axios has emerged as the go-to HTTP client for its elegance and powerful features. Let’s dive into the best practices that will help you write more maintainable and robust code with Axios.

Setting Up Axios Instances

Instead of using Axios directly, create reusable instances with predefined configurations. This approach keeps your code DRY and makes it easier to maintain consistent headers, base URLs, and timeouts across your application.

const axios = require('axios');

const api = axios.create({
  baseURL: process.env.API_BASE_URL,
  timeout: 5000,
  headers: {
    'Content-Type': 'application/json'
  }
});

Error Handling and Interceptors

One of the most crucial aspects of working with HTTP requests is proper error handling. Axios interceptors provide a clean way to handle errors globally and transform responses consistently.

api.interceptors.response.use(
  response => response,
  error => {
    if (error.response?.status === 401) {
      // Handle authentication errors
      return refreshTokenAndRetry(error);
    }
    return Promise.reject(error);
  }
);

Request Cancellation

When building responsive applications, it’s essential to handle scenarios where requests need to be cancelled. Axios provides a built-in mechanism using cancel tokens.

const CancelToken = axios.CancelToken;
const source = CancelToken.source();

api.get('/long-running-query', {
  cancelToken: source.token
}).catch(error => {
  if (axios.isCancel(error)) {
    console.log('Request cancelled:', error.message);
  }
});

// Cancel the request
source.cancel('Operation cancelled by user');

Rate Limiting and Retries

Implement rate limiting and retry mechanisms to handle API restrictions and temporary failures gracefully. You can use libraries like axios-retry or implement your own solution.

Request and Response Transformation

Use transforms to standardize your request data and response handling. This ensures consistent data formatting across your application.

const api = axios.create({
  transformRequest: [(data) => {
    // Transform request data
    return JSON.stringify(data);
  }],
  transformResponse: [(data) => {
    // Transform response data
    return JSON.parse(data);
  }]
});

Testing and Mocking

When writing tests, use axios-mock-adapter to simulate API responses. This allows you to test your code without making actual HTTP requests.

const MockAdapter = require('axios-mock-adapter');
const mock = new MockAdapter(api);

mock.onGet('/users').reply(200, {
  users: [{ id: 1, name: 'John' }]
});

Remember to always handle promises appropriately using async/await or proper promise chains, and implement proper logging for debugging and monitoring your applications in production.