How to Use node-fetch for Web Scraping
Lucas Mitchell
Automation Engineer
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
npm install node-fetchor
bash
yarn add node-fetchBasic Example: Making a GET Request
Here’s how to perform a simple GET request using node-fetch:
javascript
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
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
npm install node-fetch
npm install capsolverNow, here’s how to solve a ReCaptcha V3 and use the solution in your request:
javascript
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
npm install https-proxy-agentExample with a proxy:
javascript
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
npm install fetch-cookieExample:
javascript
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
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.
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