Web Scraper

Web Scraper

Extract data from websites using various tools.

Setup

# curl and jq are usually pre-installed or easy to install
command -v curl && command -v jq

# For browser automation (Option 4 — Playwright), install:
npx playwright install
# Or: npm install -g playwright && npx playwright install

Option 1: curl + HTML Parsing

# Get page and extract with grep/sed
curl -sL "https://example.com" | grep -oP '<title>.*?</title>'

# Extract all links
curl -sL "https://example.com" | grep -oP 'href="[^"]*"' | cut -d'"' -f2

# Extract text between tags
curl -sL "https://example.com" | sed -n '/<p>/,/<\/p>/p'

Option 2: Pup (HTML Parser)

# Install
go install github.com/ericchiang/pup@latest

# Extract elements
curl -sL "https://example.com" | pup 'title text{}'

# Extract all links
curl -sL "https://example.com" | pup 'a attr{href}'

# Extract structured data
curl -sL "https://example.com/products" | pup '.product json{}'

# Extract with CSS selectors
curl -sL "https://example.com" | pup 'div.content h1 text{}'

# Multiple attributes
curl -sL "https://example.com" | pup 'a attr{href} attr{title}'

Option 3: Python + BeautifulSoup

# scraper.py
import requests
from bs4 import BeautifulSoup
import json

url = "https://example.com"
response = requests.get(url)
soup = BeautifulSoup(response.text, 'html.parser')

# Extract title
title = soup.find('title').text

# Extract all links
links = [a.get('href') for a in soup.find_all('a', href=True)]

# Extract by class
products = soup.find_all(class_='product')
data = [{'name': p.find(class_='name').text,
         'price': p.find(class_='price').text} for p in products]

print(json.dumps(data, indent=2))

pip install beautifulsoup4 requests
python scraper.py

Option 4: Python + Playwright

# dynamic_scraper.py
from playwright.sync_api import sync_playwright
import json

with sync_playwright() as p:
    browser = p.chromium.launch()
    page = browser.new_page()
    page.goto('https://example.com')

    # Wait for dynamic content
    page.wait_for_selector('.loaded')

    # Extract data
    products = page.eval_on_selector_all('.product', '''
        items => items.map(item => ({
            name: item.querySelector('.name')?.textContent,
            price: item.querySelector('.price')?.textContent
        }))
    ''')

    print(json.dumps(products, indent=2))
    browser.close()

Handling JavaScript Sites

# Use curl with embedded JS rendering (if available)
# Or use Playwright/Puppeteer for JS-heavy sites

# Basic: check if content is in initial HTML
curl -sL "https://example.com" | grep "product"

Rate Limiting & Ethics

# Add delay between requests
for url in "${urls[@]}"; do
  curl -sL "$url" | pup 'title text{}'
  sleep 2
done

# Set user agent
curl -sL -A "Mozilla/5.0" "https://example.com"

# Respect robots.txt
curl -sL "https://example.com/robots.txt"

API-based Scraping (When Available)

# Many sites have JSON APIs - check network tab
curl -sL "https://api.example.com/v1/products" | jq '.data[]'

# Common API patterns
curl -sL "https://example.com/api/products?page=1&limit=50" | jq '.'

Tips

• Check if an API exists before scraping HTML
• Respect robots.txt and rate limits
• Use --compressed with curl for gzip support
• Add -L to follow redirects
• Use -H "Accept: application/json" for API endpoints
• Handle pagination with &page=N parameters

Triggers

scrape, scraper, web scraping, extract data, crawl website, html parsing, web extraction

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