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How to Use node-fetch for Web Scraping

How to Use node-fetch for Web Scraping

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Lucas Mitchell

Automation Engineer

27-Sep-2024

What is node-fetch?

node-fetch is a lightweight JavaScript library that brings the window.fetch API to Node.js. It is often used for making HTTP requests from a Node.js environment, providing a modern and flexible way to handle network operations asynchronously.

Features:

  • Promise-based: Uses JavaScript promises to manage asynchronous operations in a simple manner.
  • Node.js Support: Specifically designed for Node.js environments.
  • Stream Support: Supports streams, making it highly suitable for handling large data.
  • Small and Efficient: Minimalistic design, focusing on performance and compatibility with modern JavaScript features.

Prerequisites

Before using node-fetch, ensure you have:

Installation

To use node-fetch, you need to install it using npm or yarn:

bash Copy
npm install node-fetch

or

bash Copy
yarn add node-fetch

Basic Example: Making a GET Request

Here’s how to perform a simple GET request using node-fetch:

javascript Copy
const fetch = require('node-fetch');

fetch('https://httpbin.org/get')
  .then(response => response.json())
  .then(data => {
    console.log('Response Body:', data);
  })
  .catch(error => {
    console.error('Error:', error);
  });

Web Scraping Example: Fetching JSON Data from an API

Let’s fetch data from an API and log the results:

javascript Copy
const fetch = require('node-fetch');

fetch('https://jsonplaceholder.typicode.com/posts')
  .then(response => response.json())
  .then(posts => {
    posts.forEach(post => {
      console.log(`${post.title} — ${post.body}`);
    });
  })
  .catch(error => {
    console.error('Error:', error);
  });

Handling Captchas with CapSolver and node-fetch

In this section, we’ll integrate CapSolver with node-fetch to handle captchas. CapSolver provides APIs for solving captchas like ReCaptcha V3, enabling automation of tasks that require solving such captchas.

Example: Solving ReCaptcha V3 with CapSolver and node-fetch

First, install node-fetch and CapSolver:

bash Copy
npm install node-fetch
npm install capsolver

Now, here’s how to solve a ReCaptcha V3 and use the solution in your request:

javascript Copy
const fetch = require('node-fetch');
const CAPSOLVER_KEY = 'YourKey';
const PAGE_URL = 'https://antcpt.com/score_detector';
const PAGE_KEY = '6LcR_okUAAAAAPYrPe-HK_0RULO1aZM15ENyM-Mf';
const PAGE_ACTION = 'homepage';

async function createTask(url, key, pageAction) {
  try {
    const apiUrl = 'https://api.capsolver.com/createTask';
    const payload = {
      clientKey: CAPSOLVER_KEY,
      task: {
        type: 'ReCaptchaV3TaskProxyLess',
        websiteURL: url,
        websiteKey: key,
        pageAction: pageAction
      }
    };
    
    const response = await fetch(apiUrl, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(payload)
    });
    
    const data = await response.json();
    return data.taskId;

  } catch (error) {
    console.error('Error creating CAPTCHA task:', error);
    throw error;
  }
}

async function getTaskResult(taskId) {
  try {
    const apiUrl = 'https://api.capsolver.com/getTaskResult';
    const payload = {
      clientKey: CAPSOLVER_KEY,
      taskId: taskId,
    };

    let result;
    do {
      const response = await fetch(apiUrl, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(payload)
      });

      result = await response.json();
      if (result.status === 'ready') {
        return result.solution;
      }

      await new Promise(resolve => setTimeout(resolve, 5000)); // wait 5 seconds
    } while (true);

  } catch (error) {
    console.error('Error fetching CAPTCHA result:', error);
    throw error;
  }
}

async function main() {
  console.log('Creating CAPTCHA task...');
  const taskId = await createTask(PAGE_URL, PAGE_KEY, PAGE_ACTION);
  console.log(`Task ID: ${taskId}`);

  console.log('Retrieving CAPTCHA result...');
  const solution = await getTaskResult(taskId);
  const token = solution.gRecaptchaResponse;
  console.log(`Token Solution: ${token}`);

  const res = await fetch('https://antcpt.com/score_detector/verify.php', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ 'g-recaptcha-response': token })
  });

  const response = await res.json();
  console.log(`Score: ${response.score}`);
}

main().catch(err => {
  console.error(err);
});

Handling Proxies with node-fetch

To route your requests through a proxy with node-fetch, you will need a proxy agent like https-proxy-agent. Here's how to implement it:

bash Copy
npm install https-proxy-agent

Example with a proxy:

javascript Copy
const fetch = require('node-fetch');
const HttpsProxyAgent = require('https-proxy-agent');

const proxyAgent = new HttpsProxyAgent('http://username:password@proxyserver:8080');

fetch('https://httpbin.org/ip', { agent: proxyAgent })
  .then(response => response.json())
  .then(data => {
    console.log('Response Body:', data);
  })
  .catch(error => {
    console.error('Error:', error);
  });

Handling Cookies with node-fetch

For cookie handling in node-fetch, you can use a library like fetch-cookie. Here's how to use it:

bash Copy
npm install fetch-cookie

Example:

javascript Copy
const fetch = require('node-fetch');
const fetchCookie = require('fetch-cookie');
const cookieFetch = fetchCookie(fetch);

cookieFetch('https://httpbin.org/cookies/set?name=value')
  .then(response => response.json())
  .then(data => {
    console.log('Cookies:', data);
  })
  .catch(error => {
    console.error('Error:', error);
  });

Advanced Usage: Custom Headers and POST Requests

You can customize headers and perform POST requests with node-fetch:

javascript Copy
const fetch = require('node-fetch');

const headers = {
  'User-Agent': 'Mozilla/5.0 (compatible)',
  'Accept-Language': 'en-US,en;q=0.5',
};

const data = {
  username: 'testuser',
  password: 'testpass',
};

fetch('https://httpbin.org/post', {
  method: 'POST',
  headers: headers,
  body: JSON.stringify(data),
})
  .then(response => response.json())
  .then(data => {
    console.log('Response JSON:', data);
  })
  .catch(error => {
    console.error('Error:', error);
  });

Bonus Code

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Conclusion

With node-fetch, you can effectively manage HTTP requests in Node.js. By integrating it with CapSolver, you can solve captchas such as ReCaptcha V3 and captcha, providing access to restricted content. Additionally, node-fetch offers customization through headers, proxy support, and cookie management, making it a versatile tool for web scraping and automation.

Compliance Disclaimer: The information provided on this blog is for informational purposes only. CapSolver is committed to compliance with all applicable laws and regulations. The use of the CapSolver network for illegal, fraudulent, or abusive activities is strictly prohibited and will be investigated. Our captcha-solving solutions enhance user experience while ensuring 100% compliance in helping solve captcha difficulties during public data crawling. We encourage responsible use of our services. For more information, please visit our Terms of Service and Privacy Policy.

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