Web scraping javascript sites

Web Scraping JavaScript/SPA Sites

The Core Insight

For SPA/TypeScript sites: try urllib FIRST before launching a browser.

TypeScript sites (Next.js, Nuxt, React, Vue) send full HTML on first request — the content is there. Browser tools show empty snapshots because they capture before JS finishes rendering. A raw HTTP fetch often gets all the data you need.

Decision Tree

Is the site an SPA (React/Next/Nuxt/Vue)?
│
├── YES → Try urllib/requests FIRST
│         └─ Got content? → DONE
│         └─ Content empty? → Use Playwright
│
└── NO (static HTML) → Use urllib/requests directly

Layer 1: Raw HTML Fetch (Fastest)

import urllib.request
import re

url = "https://example.com"
req = urllib.request.Request(url, headers={
    'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36'
})
response = urllib.request.urlopen(req, timeout=10)
html = response.read().decode('utf-8')

# Extract content
# Option A: regex search
prices = re.findall(r'€[\d,]+', html)

# Option B: find section context
section = re.search(r'id="pricing".{0,5000}', html, re.DOTALL | re.IGNORECASE)
if section:
    content = re.sub(r'<[^>]+>', ' ', section.group())
    content = re.sub(r'\s+', ' ', content).strip()

# Option C: parse HTML properly
from html.parser import HTMLParser
class ContentParser(HTMLParser):
    def __init__(self):
        super().__init__()
        self.in_target = False
        self.text = []
    def handle_starttag(self, tag, attrs):
        if tag in ('h1','h2','h3','p', 'li'):
            self.in_target = True
    def handle_data(self, data):
        if self.in_target:
            self.text.append(data.strip())
    def handle_endtag(self, tag):
        if tag in ('h1','h2','h3','p', 'li'):
            self.in_target = False

Why urllib Often Works for "Lazy" Sites

Many TypeScript/React sites pre-render HTML on the server (SSR) or send full content in initial HTML, but use JS to make it look animated/lazy. The data is in the first response — you just need to parse it.

Layer 2: Playwright (When Needed)

Use when:

• Content loads via AJAX/fetch calls AFTER page load
• Content requires user interaction (click to expand, scroll, login)
• Site has strong bot detection
• Single-page app with client-side routing

Setup

from playwright.sync_api import sync_playwright

with sync_playwright() as p:
    browser = p.chromium.launch(headless=True)
    page = browser.new_page()
    
    # Human-like headers
    page.set_extra_http_headers({
        "Accept-Language": "en-US,en;q=0.9",
        "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"
    })
    page.set_viewport_size({"width": 1920, "height": 1080})
    
    # Navigate and wait properly
    page.goto(url, wait_until='networkidle', timeout=30000)
    
    # Wait for specific content (NOT just page load)
    page.wait_for_selector(".pricing-card", timeout=10000)
    
    # Extract
    content = page.text_content("body")
    
    browser.close()

Waiting Patterns (Humanize)

# ❌ Robot: instant read after click
page.click("button")
result = page.text_content(".result")  # Empty!

# ✅ Human: wait for DOM change
page.click("button")
page.wait_for_selector(".result:not(:empty)", timeout=5000)
result = page.text_content(".result")

# ❌ Robot: no wait
page.goto(url)
title = page.text_content("h1")

# ✅ Human: wait for content
page.goto(url)
page.wait_for_selector("h1", timeout=10000)
title = page.text_content("h1")

Scroll Like a Human

for _ in range(3):
    page.mouse.wheel(0, 500)
    page.wait_for_timeout(300)

Hover Before Click (Pass Sophisticated Bot Detection)

page.hover("nav .menu-item")
page.wait_for_timeout(100)
page.click("nav .menu-item")

Stealth Mode (Puppeteer Extra)

For sites with bot detection:

const puppeteer = require('puppeteer-extra');
const StealthPlugin = require('puppeteer-extra-plugin-stealth');
puppeteer.use(StealthPlugin());

(async () => {
  const browser = await puppeteer.launch({ 
    headless: 'new',
    args: ['--no-sandbox', '--disable-setuid-sandbox']
  });
  const page = await browser.newPage();
  await page.goto('https://bot-detected-site.com');
  // ...
})();

Available at: $HERMES_AGENT_DIR/node_modules/puppeteer-extra-plugin-stealth

TypeScript Site Patterns

Next.js Static Export

# These are fully scrapeable with urllib - HTML is complete
page.goto("https://site.com/page")
# Content is in initial HTML

Next.js SSR

# Server renders full HTML - urllib works
page.goto("https://site.com/page")

Client-Side Only (CRA/Vite)

# Must use Playwright - no HTML content without JS
page.goto("https://site.com/page")
page.wait_for_selector(".content")

Nuxt/Vue

# Often SSR with hydration - urllib works
page.goto("https://site.com/page")

Common Issues

Issue	Solution
Element not found	Add wait_for_selector() before interacting
Page loads blank	Use wait_until='networkidle'
Bot detection	Use puppeteer-extra with StealthPlugin
Lazy loading	Scroll or wait for specific element
Cloudflare challenge	Try fetching Cloudflare clearance cookie first, or use Playwright
CAPTCHA	Cannot be bypassed programmatically in most cases

Bot Detection Bypass

# Try these headers
headers = {
    'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36',
    'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8',
    'Accept-Language': 'en-US,en;q=0.9',
    'Accept-Encoding': 'gzip, deflate, br',
    'Connection': 'keep-alive',
    'Upgrade-Insecure-Requests': '1',
    'Sec-Fetch-Dest': 'document',
    'Sec-Fetch-Mode': 'navigate',
    'Sec-Fetch-Site': 'none',
    'Sec-Fetch-User': '?1',
    'Cache-Control': 'max-age=0',
}

Tools Available on Appie-3 VPS

Tool	Location	Use
playwright	$HERMES_AGENT_DIR/node_modules/playwright	Browser automation
puppeteer-extra + stealth	Same	Bot-evasion browser
httpx	Python venv	Async HTTP
requests	Python venv	Simple HTTP
urllib	Python stdlib	Raw HTML fetch

Quick Test Script

#!/usr/bin/env python3
"""Test if a site is scrapeable with urllib or needs Playwright"""

import urllib.request
import sys

def test_site(url):
    req = urllib.request.Request(url, headers={
        'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36'
    })
    try:
        response = urllib.request.urlopen(req, timeout=10)
        html = response.read().decode('utf-8')
        print(f"SUCCESS: {len(html)} bytes received")
        
        # Check for meaningful content
        if len(html) < 5000:
            print("WARNING: Very small HTML - likely needs JS rendering")
            return False
        
        # Check for text content
        import re
        text = re.sub(r'<[^>]+>', '', html)
        text = re.sub(r'\s+', ' ', text).strip()
        print(f"Text content: {len(text)} chars")
        
        if text.count(' ') < 50:
            print("WARNING: Little text content - likely JS-rendered SPA")
            return False
            
        return True
    except Exception as e:
        print(f"ERROR: {e}")
        return False

if __name__ == "__main__":
    url = sys.argv[1] if len(sys.argv) > 1 else "https://example.com/app"
    print(f"Testing: {url}")
    can_scrape = test_site(url)
    print(f"\nRecommendation: {'urllib works' if can_scrape else 'Use Playwright'}")

Run: python3 $HERMES_SKILLS_DIR/web-scraping-javascript-sites/scripts/test-site.py https://example.com

See Also

• skills/playwright — Full Playwright reference
• skills/ui-ux-pro-max — For taking screenshots of scraped sites