web-scraper（网络爬虫）

Web Scraper

A toolkit for extracting content from web pages using Python.

When to Use This Skill

Activate this skill when the user needs to:

• Fetch the HTML content of a web page
• Extract all links from a page
• Get readable text content from HTML
• Scrape data from websites
• Download and analyze web content

Requirements

This skill requires external packages:

pip install requests beautifulsoup4

Available Scripts

Always run scripts with --help first to see all available options.

Decision Tree

Task → What do you need?
    │
    ├─ Raw HTML content?
    │   └─ Use: fetch_page.py <url>
    │
    ├─ List of links on a page?
    │   └─ Use: extract_links.py <url>
    │
    └─ Text content (no HTML tags)?
        └─ Use: extract_text.py <url>

Quick Examples

Fetch page HTML:

python scripts/fetch_page.py https://example.com
python scripts/fetch_page.py https://example.com --output page.html

Extract all links:

python scripts/extract_links.py https://example.com
python scripts/extract_links.py https://example.com --absolute --filter "\.pdf$"

Extract text content:

python scripts/extract_text.py https://example.com
python scripts/extract_text.py https://example.com --paragraphs

Best Practices

1. Respect robots.txt - Check if scraping is allowed
2. Add delays - Don't overwhelm servers with rapid requests
3. Use appropriate User-Agent - Identify your scraper properly
4. Handle errors gracefully - Websites may block or timeout
5. Cache responses - Don't re-fetch unchanged pages

Common Issues

• 403 Forbidden: Site may be blocking scrapers. Try with --user-agent flag.
• Timeout: Site may be slow. Increase --timeout value.
• Empty content: Page may require JavaScript. These scripts handle static HTML only.
• Encoding issues: Use --encoding flag if text appears garbled.

Reference Files

See references/selectors.md for CSS selector syntax reference.

Ethical Considerations

• Only scrape public data
• Respect rate limits and robots.txt
• Don't scrape personal/private information
• Check website terms of service
• Consider using official APIs when available