Is it possible to create a JavaScript web crawler?

General Discussions
1

Is it possible to create a JavaScript web crawler? I want to crawl a page, check for the hyperlinks on that page, follow those hyperlinks, and capture data from the resulting pages.

2

Hey ,

Using Node.js with Axios and Cheerio: You can create a javascript web crawler using Node.js by utilizing libraries like Axios for HTTP requests and Cheerio for parsing HTML. First, you fetch the webpage using Axios, then load the HTML with Cheerio to extract hyperlinks. You can follow those hyperlinks recursively to crawl additional pages.

const axios = require('axios');
const cheerio = require('cheerio');

async function crawl(url) {
    const response = await axios.get(url);
    const $ = cheerio.load(response.data);
    const links = [];
    
    $('a').each((i, link) => {
        links.push($(link).attr('href'));
    });

    console.log(links);
    // Call crawl() for each link if needed
}

crawl(‘https://example.com’);

3

Based on my experience, you can also use Puppeteer, as it is a headless browser that allows you to control Chrome or Chromium. This can be an effective way to create a javascript web crawler that interacts with pages just like a user would, allowing you to scrape dynamic content and follow links easily.

const puppeteer = require('puppeteer');

async function crawl(url) {
    const browser = await puppeteer.launch();
    const page = await browser.newPage();
    await page.goto(url);

    const links = await page.evaluate(() => {
        return Array.from(document.querySelectorAll('a')).map(a => a.href);
    });

    console.log(links);
    await browser.close();
}

crawl(‘https://example.com’);

4

You can also Scrapy with a JavaScript Integration:

While Scrapy is a Python-based framework, you can integrate it with a JavaScript web crawler by using the Scrapy Splash component. This allows you to render JavaScript content and extract data. Set up Scrapy to call a Splash service for crawling pages that require JavaScript execution.

import scrapy
from scrapy_splash import SplashRequest

class MySpider(scrapy.Spider):
    name = 'my_spider'

    def start_requests(self):
        yield SplashRequest('https://example.com', self.parse)

    def parse(self, response):
        links = response.css('a::attr(href)').getall()
        print(links)
        # Follow the links if needed