Setting up custom Axios instances in Node.js

Working with HTTP requests in Node.js applications can sometimes feel overwhelming, especially when you’re dealing with multiple API endpoints or different authentication methods. That’s where custom Axios instances come in - they’re like your personal request helpers that keep your code clean and maintainable.

Why Use Custom Axios Instances?

Think of custom Axios instances as creating your own specialized HTTP client. Instead of configuring the same settings repeatedly for each request, you can set them up once and reuse them throughout your application. It’s like having a dedicated assistant who knows exactly how to handle specific types of requests.

Setting Up Your First Custom Instance

Let’s dive into creating your first custom Axios instance. Here’s how you can set one up:

const axios = require('axios');

const apiClient = axios.create({
  baseURL: 'https://api.example.com',
  timeout: 5000,
  headers: {
    'Content-Type': 'application/json',
    'Accept': 'application/json'
  }
});

Advanced Configuration

Custom instances become even more powerful when you need to handle different APIs or authentication methods. Here’s how you can create multiple instances for different purposes:

// Instance for public API
const publicApi = axios.create({
  baseURL: 'https://public-api.example.com',
  timeout: 3000
});

// Instance for authenticated requests
const privateApi = axios.create({
  baseURL: 'https://private-api.example.com',
  timeout: 5000,
  headers: {
    'Authorization': `Bearer ${process.env.API_TOKEN}`
  }
});

Interceptors: Adding Super Powers

One of the most powerful features of custom Axios instances is the ability to add interceptors. These are like middleware that can modify requests or responses before they’re handled:

apiClient.interceptors.request.use(
  config => {
    // Add timestamp to requests
    config.headers['Request-Time'] = new Date().toISOString();
    return config;
  },
  error => {
    return Promise.reject(error);
  }
);

apiClient.interceptors.response.use(
  response => {
    // Transform response data
    return response.data;
  },
  error => {
    // Handle errors globally
    console.error('API Error:', error.message);
    return Promise.reject(error);
  }
);

Best Practices

1. Keep your instances organized in separate files
2. Use environment variables for sensitive information
3. Implement proper error handling
4. Set reasonable timeouts
5. Use interceptors wisely

By following these practices, you’ll create a robust and maintainable HTTP client structure in your Node.js applications.