JavaScript, forms, and dynamic pages

Part 1 covered static HTML. This part deals with sites that don’t hand you clean markup: rendering JavaScript with Splash, submitting forms and holding sessions, and pulling data straight from the AJAX endpoints that actually hold it.

What this part covers

JavaScript rendering with Scrapy-Splash integration
Handling forms, logins, and session management
Extracting data from AJAX requests and APIs
Advanced selector techniques and data extraction
Custom middleware development
Handling cookies, headers, and authentication
Working with infinite scroll and pagination

JavaScript-Heavy Websites with Scrapy-Splash

Scrapy alone cannot execute JavaScript. For pages that render their content client-side, Scrapy-Splash fills the gap.

Setting Up Splash

# Install Docker (required for Splash)
# On macOS with Homebrew:
brew install docker

# Start Docker service and run Splash
docker run -p 8050:8050 scrapinghub/splash

# Install Scrapy-Splash
pip install scrapy-splash

Configuring Scrapy for Splash

# Splash settings
SPLASH_URL = 'http://localhost:8050'

# Enable Splash middleware
DOWNLOADER_MIDDLEWARES = {
    'scrapy_splash.SplashCookiesMiddleware': 723,
    'scrapy_splash.SplashMiddleware': 725,
    'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware': 810,
}

# Enable Splash spider middleware
SPIDER_MIDDLEWARES = {
    'scrapy_splash.SplashDeduplicateArgsMiddleware': 100,
}

# Splash duplicate filter
DUPEFILTER_CLASS = 'scrapy_splash.SplashAwareDupeFilter'

# Splash HTTP cache storage backend
HTTPCACHE_STORAGE = 'scrapy_splash.SplashAwareFSCacheStorage'

JavaScript-Enabled Spider

import scrapy
from scrapy_splash import SplashRequest
from webscraper.items import ProductItem
from scrapy.loader import ItemLoader
import json

class SPASpider(scrapy.Spider):
    name = 'spa_scraper'
    allowed_domains = ['example-spa.com']

    custom_settings = {
        'DOWNLOAD_DELAY': 2,
        'SPLASH_URL': 'http://localhost:8050',
    }

    def start_requests(self):
        urls = ['https://example-spa.com/products']

        # Lua script for complex interactions
        lua_script = """
        function main(splash, args)
            splash.private_mode_enabled = false
            splash:go(args.url)
            splash:wait(3)

            -- Wait for products to load
            splash:wait_for_resume([[
                function main(splash) {
                    var products = document.querySelectorAll('.product-item');
                    if (products.length > 0) {
                        splash.resume('Products loaded');
                    } else {
                        setTimeout(function() {
                            splash.resume('Timeout');
                        }, 10000);
                    }
                }
            ]], 15)

            -- Scroll to load more content
            splash:runjs([[
                window.scrollTo(0, document.body.scrollHeight);
            ]])
            splash:wait(2)

            -- Click "Load More" button if present
            local load_more = splash:select('.load-more-btn')
            if load_more then
                load_more:click()
                splash:wait(3)
            end

            return {
                html = splash:html(),
                png = splash:png(),
                har = splash:har(),
                url = splash:url()
            }
        end
        """

        for url in urls:
            yield SplashRequest(
                url=url,
                callback=self.parse,
                args={
                    'lua_source': lua_script,
                    'timeout': 30,
                    'resource_timeout': 10,
                    'wait': 5,
                }
            )

    def parse(self, response):
        """Parse SPA product listings"""
        self.logger.info(f'Parsing SPA page: {response.url}')

        # Extract products from JavaScript-rendered content
        products = response.css('.product-item')

        for product in products:
            product_url = product.css('a::attr(href)').get()
            if product_url:
                # Use SplashRequest for product pages too
                yield SplashRequest(
                    url=response.urljoin(product_url),
                    callback=self.parse_product,
                    args={'wait': 3}
                )

        # Handle pagination in SPA
        next_page_data = response.css('script[type="application/json"]::text').get()
        if next_page_data:
            try:
                data = json.loads(next_page_data)
                if data.get('nextPage'):
                    yield SplashRequest(
                        url=data['nextPage'],
                        callback=self.parse,
                        args={'wait': 3}
                    )
            except json.JSONDecodeError:
                pass

    def parse_product(self, response):
        """Parse individual product from SPA"""
        loader = ItemLoader(item=ProductItem(), response=response)

        # Extract data that might be loaded via JavaScript
        loader.add_css('name', 'h1.product-title::text')
        loader.add_css('price', '.price-display::text')
        loader.add_css('description', '.product-description::text')

        # Extract from JavaScript variables
        js_data = self.extract_js_data(response)
        if js_data:
            loader.add_value('name', js_data.get('productName'))
            loader.add_value('price', js_data.get('price'))
            loader.add_value('sku', js_data.get('sku'))

        loader.add_value('url', response.url)
        loader.add_value('source', 'spa')

        yield loader.load_item()

    def extract_js_data(self, response):
        """Extract data from JavaScript variables"""
        # Look for common patterns
        js_patterns = [
            r'window\.productData\s*=\s*({[^}]+})',
            r'var\s+product\s*=\s*({[^}]+})',
            r'__INITIAL_STATE__\s*=\s*({.+?});'
        ]

        for pattern in js_patterns:
            import re
            match = re.search(pattern, response.text)
            if match:
                try:
                    return json.loads(match.group(1))
                except json.JSONDecodeError:
                    continue

        return None

Form Handling and Authentication

Many sites put the useful data behind a login or a search form. Here’s how to handle both:

import scrapy
from scrapy import FormRequest
from webscraper.items import ProductItem

class LoginSpider(scrapy.Spider):
    name = 'login_scraper'
    allowed_domains = ['secure-store.com']
    start_urls = ['https://secure-store.com/login']

    def parse(self, response):
        """Handle login form"""
        # Check if already logged in
        if self.is_logged_in(response):
            return self.after_login(response)

        # Extract form data and CSRF tokens
        csrf_token = response.css('input[name="csrf_token"]::attr(value)').get()

        # Submit login form
        return FormRequest.from_response(
            response,
            formdata={
                'username': 'your_username',
                'password': 'your_password',
                'csrf_token': csrf_token,
                'remember_me': '1'
            },
            callback=self.after_login,
            dont_filter=True
        )

    def is_logged_in(self, response):
        """Check if successfully logged in"""
        return bool(response.css('.user-dashboard'))

    def after_login(self, response):
        """Handle post-login logic"""
        if not self.is_logged_in(response):
            self.logger.error('Login failed')
            return

        self.logger.info('Successfully logged in')

        # Navigate to protected areas
        protected_urls = [
            'https://secure-store.com/members/products',
            'https://secure-store.com/premium/catalog'
        ]

        for url in protected_urls:
            yield response.follow(url, callback=self.parse_protected_content)

    def parse_protected_content(self, response):
        """Parse content that requires authentication"""
        products = response.css('.premium-product')

        for product in products:
            loader = ItemLoader(item=ProductItem(), selector=product)
            loader.add_css('name', '.product-name::text')
            loader.add_css('price', '.member-price::text')
            loader.add_css('description', '.product-desc::text')
            loader.add_value('source', 'premium')

            yield loader.load_item()

Complex Form Handling

import scrapy
from scrapy import FormRequest
import json

class FormSpider(scrapy.Spider):
    name = 'form_handler'

    def start_requests(self):
        # Start with a search form
        yield scrapy.Request(
            'https://example.com/search',
            callback=self.parse_search_form
        )

    def parse_search_form(self, response):
        """Handle complex search forms"""
        # Extract all form fields and hidden values
        form_data = {}

        # Get all input fields
        for input_field in response.css('form input'):
            name = input_field.css('::attr(name)').get()
            value = input_field.css('::attr(value)').get()
            input_type = input_field.css('::attr(type)').get()

            if name:
                if input_type == 'checkbox' and not input_field.css('::attr(checked)').get():
                    continue  # Skip unchecked checkboxes
                form_data[name] = value or ''

        # Get select fields
        for select in response.css('form select'):
            name = select.css('::attr(name)').get()
            selected = select.css('option[selected]::attr(value)').get()
            if name:
                form_data[name] = selected or ''

        # Add our search parameters
        search_params = {
            'query': 'laptops',
            'category': 'electronics',
            'price_min': '500',
            'price_max': '2000',
            'sort': 'price_desc'
        }
        form_data.update(search_params)

        # Submit form
        yield FormRequest.from_response(
            response,
            formdata=form_data,
            callback=self.parse_search_results
        )

    def parse_search_results(self, response):
        """Parse search results"""
        products = response.css('.search-result-item')

        for product in products:
            # Extract product details
            product_data = {
                'name': product.css('.product-title::text').get(),
                'price': product.css('.price::text').get(),
                'rating': product.css('.rating::attr(data-rating)').get(),
                'url': response.urljoin(product.css('a::attr(href)').get())
            }

            if product_data['url']:
                yield response.follow(
                    product_data['url'],
                    callback=self.parse_product,
                    meta={'product_data': product_data}
                )

AJAX Requests and API Integration

When a site loads its data via AJAX, hitting the API directly is usually faster and more reliable than rendering the page. Here’s how to find and work with those requests:

AJAX Spider

import scrapy
import json
from urllib.parse import urlencode

class AjaxSpider(scrapy.Spider):
    name = 'ajax_scraper'
    allowed_domains = ['api-example.com']

    def start_requests(self):
        # Start with the main page to get initial data
        yield scrapy.Request(
            'https://api-example.com/products',
            callback=self.parse_initial_page
        )

    def parse_initial_page(self, response):
        """Extract API endpoints and initial data"""
        # Look for API endpoints in JavaScript
        api_endpoints = self.extract_api_endpoints(response)

        # Extract pagination info
        total_pages = response.css('.pagination::attr(data-total-pages)').get()
        if total_pages:
            total_pages = int(total_pages)
        else:
            total_pages = 10  # Default fallback

        # Generate API requests for all pages
        for page in range(1, total_pages + 1):
            api_url = f'https://api-example.com/api/products'
            params = {
                'page': page,
                'limit': 20,
                'format': 'json'
            }

            url = f"{api_url}?{urlencode(params)}"
            yield scrapy.Request(
                url=url,
                callback=self.parse_api_response,
                headers={
                    'Accept': 'application/json',
                    'X-Requested-With': 'XMLHttpRequest',
                    'Referer': response.url
                }
            )

    def extract_api_endpoints(self, response):
        """Extract API endpoints from JavaScript"""
        endpoints = []

        # Common patterns for API endpoints
        import re
        patterns = [
            r'api[\'"]:\s*[\'"]([^\'\"]+)',
            r'endpoint[\'"]:\s*[\'"]([^\'\"]+)',
            r'fetch\([\'"]([^\'\"]+)',
            r'axios\.get\([\'"]([^\'\"]+)'
        ]

        for pattern in patterns:
            matches = re.findall(pattern, response.text)
            endpoints.extend(matches)

        return list(set(endpoints))  # Remove duplicates

    def parse_api_response(self, response):
        """Parse JSON API responses"""
        try:
            data = json.loads(response.text)
        except json.JSONDecodeError:
            self.logger.error(f'Invalid JSON response from {response.url}')
            return

        # Handle different API response structures
        products = data.get('products', data.get('data', data.get('items', [])))

        for product in products:
            # Create item from API data
            product_item = {
                'id': product.get('id'),
                'name': product.get('name', product.get('title')),
                'price': product.get('price'),
                'description': product.get('description'),
                'category': product.get('category'),
                'images': product.get('images', []),
                'url': product.get('url'),
                'api_source': response.url
            }

            yield product_item

        # Handle API pagination
        pagination = data.get('pagination', {})
        if pagination.get('hasNextPage'):
            next_page = pagination.get('nextPage')
            if next_page:
                yield response.follow(
                    next_page,
                    callback=self.parse_api_response
                )

Real-time Data Spider

import scrapy
import json
import time
from datetime import datetime

class RealtimeSpider(scrapy.Spider):
    name = 'realtime_scraper'

    custom_settings = {
        'DOWNLOAD_DELAY': 5,  # Respectful delay for real-time data
        'CONCURRENT_REQUESTS': 1,  # Sequential requests for real-time
    }

    def start_requests(self):
        # Monitor real-time endpoints
        endpoints = [
            'https://api.example.com/live/stock-prices',
            'https://api.example.com/live/crypto-prices',
            'https://api.example.com/live/forex-rates'
        ]

        for endpoint in endpoints:
            yield scrapy.Request(
                endpoint,
                callback=self.parse_realtime_data,
                meta={
                    'endpoint_type': self.get_endpoint_type(endpoint),
                    'start_time': time.time()
                }
            )

    def get_endpoint_type(self, endpoint):
        """Determine endpoint type from URL"""
        if 'stock' in endpoint:
            return 'stocks'
        elif 'crypto' in endpoint:
            return 'cryptocurrency'
        elif 'forex' in endpoint:
            return 'forex'
        return 'unknown'

    def parse_realtime_data(self, response):
        """Parse real-time financial data"""
        try:
            data = json.loads(response.text)
        except json.JSONDecodeError:
            return

        endpoint_type = response.meta['endpoint_type']
        timestamp = datetime.now().isoformat()

        # Process based on endpoint type
        if endpoint_type == 'stocks':
            yield from self.process_stock_data(data, timestamp)
        elif endpoint_type == 'cryptocurrency':
            yield from self.process_crypto_data(data, timestamp)
        elif endpoint_type == 'forex':
            yield from self.process_forex_data(data, timestamp)

        # Schedule next request for continuous monitoring
        yield scrapy.Request(
            response.url,
            callback=self.parse_realtime_data,
            meta=response.meta,
            dont_filter=True  # Allow duplicate requests
        )

    def process_stock_data(self, data, timestamp):
        """Process stock price data"""
        stocks = data.get('stocks', [])

        for stock in stocks:
            yield {
                'type': 'stock',
                'symbol': stock.get('symbol'),
                'price': stock.get('price'),
                'change': stock.get('change'),
                'change_percent': stock.get('changePercent'),
                'volume': stock.get('volume'),
                'timestamp': timestamp,
                'market_cap': stock.get('marketCap')
            }

    def process_crypto_data(self, data, timestamp):
        """Process cryptocurrency data"""
        currencies = data.get('data', [])

        for currency in currencies:
            yield {
                'type': 'cryptocurrency',
                'symbol': currency.get('symbol'),
                'name': currency.get('name'),
                'price_usd': currency.get('price_usd'),
                'price_btc': currency.get('price_btc'),
                'volume_24h': currency.get('24h_volume_usd'),
                'market_cap': currency.get('market_cap_usd'),
                'change_24h': currency.get('percent_change_24h'),
                'timestamp': timestamp
            }

    def process_forex_data(self, data, timestamp):
        """Process forex rates data"""
        rates = data.get('rates', {})
        base_currency = data.get('base', 'USD')

        for currency, rate in rates.items():
            yield {
                'type': 'forex',
                'base_currency': base_currency,
                'target_currency': currency,
                'rate': rate,
                'timestamp': timestamp
            }

Advanced Selector Techniques

Complex XPath and CSS Selectors

# Advanced selector utilities
class AdvancedSelectors:

    @staticmethod
    def extract_with_fallbacks(response, selectors):
        """Try multiple selectors until one works"""
        for selector in selectors:
            if selector.startswith('//'):
                # XPath selector
                result = response.xpath(selector).get()
            else:
                # CSS selector
                result = response.css(selector).get()

            if result:
                return result.strip()
        return None

    @staticmethod
    def extract_text_near_element(response, anchor_text, search_area='following'):
        """Extract text near a specific element"""
        if search_area == 'following':
            xpath = f"//text()[contains(., '{anchor_text}')]/following::text()[1]"
        elif search_area == 'preceding':
            xpath = f"//text()[contains(., '{anchor_text}')]/preceding::text()[1]"
        elif search_area == 'parent':
            xpath = f"//text()[contains(., '{anchor_text}')]/parent::*/text()"

        return response.xpath(xpath).get()

    @staticmethod
    def extract_table_data(response, table_selector):
        """Extract structured data from tables"""
        table = response.css(table_selector)
        if not table:
            return []

        headers = table.css('thead tr th::text').getall()
        if not headers:
            headers = table.css('tr:first-child td::text').getall()

        rows = []
        for row in table.css('tbody tr, tr')[1:]:  # Skip header row
            cells = row.css('td::text').getall()
            if len(cells) == len(headers):
                row_data = dict(zip(headers, cells))
                rows.append(row_data)

        return rows

    @staticmethod
    def extract_nested_json(response, script_selector):
        """Extract JSON data from script tags"""
        scripts = response.css(script_selector)

        for script in scripts:
            content = script.get()
            # Try to find JSON objects
            import re
            import json

            json_patterns = [
                r'var\s+\w+\s*=\s*({.+?});',
                r'window\.\w+\s*=\s*({.+?});',
                r'data:\s*({.+?})',
            ]

            for pattern in json_patterns:
                matches = re.findall(pattern, content, re.DOTALL)
                for match in matches:
                    try:
                        return json.loads(match)
                    except json.JSONDecodeError:
                        continue

        return None

# Usage in spider
def parse_complex_page(self, response):
    """Example using advanced selectors"""
    selectors = AdvancedSelectors()

    # Try multiple price selectors
    price = selectors.extract_with_fallbacks(response, [
        '.price-current::text',
        '.price::text',
        '//span[@class="price"]//text()',
        '.product-price .value::text'
    ])

    # Extract text near "Price:" label
    price_alt = selectors.extract_text_near_element(response, 'Price:', 'following')

    # Extract table data
    specs = selectors.extract_table_data(response, '.specifications-table')

    # Extract JSON configuration
    config = selectors.extract_nested_json(response, 'script[type="application/json"]')

    yield {
        'price': price or price_alt,
        'specifications': specs,
        'config': config
    }

Custom Middleware Development

Rotation Middleware

import random
import time
from scrapy.downloadermiddlewares.useragent import UserAgentMiddleware
from scrapy.exceptions import NotConfigured

class RotatingUserAgentMiddleware(UserAgentMiddleware):
    """Rotate user agents to avoid detection"""

    def __init__(self, user_agent=''):
        self.user_agent = user_agent

        # List of realistic user agents
        self.user_agent_list = [
            'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36',
            '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',
            'Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/121.0',
            'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.1 Safari/605.1.15',
            'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36',
        ]

    def process_request(self, request, spider):
        ua = random.choice(self.user_agent_list)
        request.headers['User-Agent'] = ua
        return None

class ProxyRotationMiddleware:
    """Rotate proxies to distribute requests"""

    def __init__(self, proxy_list=None):
        if not proxy_list:
            raise NotConfigured('No proxy list provided')

        self.proxy_list = proxy_list
        self.proxy_index = 0

    @classmethod
    def from_crawler(cls, crawler):
        proxy_list = crawler.settings.getlist('PROXY_LIST')
        return cls(proxy_list)

    def process_request(self, request, spider):
        proxy = self.proxy_list[self.proxy_index]
        self.proxy_index = (self.proxy_index + 1) % len(self.proxy_list)

        request.meta['proxy'] = proxy
        spider.logger.debug(f'Using proxy: {proxy}')

class RetryWithBackoffMiddleware:
    """Implement exponential backoff for retries"""

    def __init__(self, max_retry_times=3, initial_delay=1):
        self.max_retry_times = max_retry_times
        self.initial_delay = initial_delay

    @classmethod
    def from_crawler(cls, crawler):
        return cls(
            max_retry_times=crawler.settings.getint('RETRY_TIMES', 3),
            initial_delay=crawler.settings.getfloat('RETRY_INITIAL_DELAY', 1)
        )

    def process_response(self, request, response, spider):
        if response.status in [429, 503, 502, 504]:  # Rate limited or server errors
            retry_times = request.meta.get('retry_times', 0)

            if retry_times < self.max_retry_times:
                # Calculate exponential backoff delay
                delay = self.initial_delay * (2 ** retry_times)
                spider.logger.info(f'Retrying {request.url} after {delay}s (attempt {retry_times + 1})')

                # Add delay
                time.sleep(delay)

                # Create retry request
                retry_request = request.copy()
                retry_request.meta['retry_times'] = retry_times + 1
                retry_request.dont_filter = True

                return retry_request

        return response

class HeaderRotationMiddleware:
    """Rotate request headers to appear more natural"""

    def __init__(self):
        self.header_sets = [
            {
                'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
                'Accept-Language': 'en-US,en;q=0.5',
                'Accept-Encoding': 'gzip, deflate',
                'DNT': '1',
                'Connection': 'keep-alive',
                'Upgrade-Insecure-Requests': '1',
            },
            {
                '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',
                'Sec-Fetch-Dest': 'document',
                'Sec-Fetch-Mode': 'navigate',
                'Sec-Fetch-Site': 'none',
            }
        ]

    def process_request(self, request, spider):
        headers = random.choice(self.header_sets)
        for key, value in headers.items():
            request.headers[key] = value

        return None

Infinite Scroll and Dynamic Loading

import scrapy
from scrapy_splash import SplashRequest
import json

class InfiniteScrollSpider(scrapy.Spider):
    name = 'infinite_scroll'
    allowed_domains = ['infinite-example.com']

    def start_requests(self):
        lua_script = """
        function main(splash, args)
            splash:go(args.url)
            splash:wait(2)

            -- Function to scroll and wait for content
            local function scroll_and_wait(times)
                for i = 1, times do
                    splash:runjs([[
                        window.scrollTo(0, document.body.scrollHeight);
                    ]])
                    splash:wait(2)

                    -- Check if "Load More" button exists and click it
                    local load_more = splash:select('.load-more')
                    if load_more then
                        load_more:click()
                        splash:wait(3)
                    end

                    -- Check if reached end
                    local end_marker = splash:select('.end-of-content')
                    if end_marker then
                        break
                    end
                end
            end

            -- Scroll multiple times to load content
            scroll_and_wait(5)

            return {
                html = splash:html(),
                url = splash:url()
            }
        end
        """

        yield SplashRequest(
            url='https://infinite-example.com/products',
            callback=self.parse,
            args={
                'lua_source': lua_script,
                'timeout': 60
            }
        )

    def parse(self, response):
        """Parse infinite scroll content"""
        products = response.css('.product-item')

        for product in products:
            yield {
                'name': product.css('.product-name::text').get(),
                'price': product.css('.price::text').get(),
                'url': response.urljoin(product.css('a::attr(href)').get())
            }

        # Look for AJAX endpoints to continue pagination
        self.extract_ajax_pagination(response)

    def extract_ajax_pagination(self, response):
        """Extract AJAX pagination endpoints"""
        import re

        # Look for pagination API endpoints in JavaScript
        ajax_patterns = [
            r'loadMore[\'\"]\s*:\s*[\'\"](.*?)[\'\"',
            r'pagination[\'\"]\s*:\s*[\'\"](.*?)[\'\"',
            r'nextPage[\'\"]\s*:\s*[\'\"](.*?)[\'\"'
        ]

        for pattern in ajax_patterns:
            matches = re.findall(pattern, response.text)
            for match in matches:
                if match.startswith('http') or match.startswith('/'):
                    yield scrapy.Request(
                        url=response.urljoin(match),
                        callback=self.parse_ajax_page,
                        headers={'X-Requested-With': 'XMLHttpRequest'}
                    )

    def parse_ajax_page(self, response):
        """Parse AJAX loaded content"""
        try:
            data = json.loads(response.text)

            # Extract HTML content from AJAX response
            html_content = data.get('html', '')
            if html_content:
                from scrapy import Selector
                selector = Selector(text=html_content)

                products = selector.css('.product-item')
                for product in products:
                    yield {
                        'name': product.css('.product-name::text').get(),
                        'price': product.css('.price::text').get(),
                        'ajax_source': True
                    }

            # Continue pagination if available
            next_page = data.get('nextPage')
            if next_page:
                yield response.follow(
                    next_page,
                    callback=self.parse_ajax_page
                )

        except json.JSONDecodeError:
            self.logger.error(f'Invalid JSON from {response.url}')

Summary

You can now render JavaScript pages through Splash, authenticate and keep sessions, pull data straight from AJAX endpoints, and write middleware for rotation and retries. That handles most sites; the ones that actively fight back are next.

What’s Next?

Part 3: Anti-Detection and Scaling covers:

Advanced anti-detection techniques
Distributed scraping with Scrapy-Redis
Monitoring and alerting systems
Performance optimization strategies
Legal compliance and ethical scraping

Practice Exercise

Build a spider that can handle a modern e-commerce site with:

JavaScript-rendered product listings
User authentication for member prices
AJAX-loaded reviews and ratings
Infinite scroll pagination
Form-based search functionality

Scrapy, part 2: JavaScript, forms, and dynamic pages

Prerequisites

JavaScript, forms, and dynamic pages

What this part covers

JavaScript-Heavy Websites with Scrapy-Splash

Setting Up Splash

Configuring Scrapy for Splash

JavaScript-Enabled Spider

Form Handling and Authentication

Complex Form Handling

AJAX Requests and API Integration

AJAX Spider

Real-time Data Spider

Advanced Selector Techniques

Complex XPath and CSS Selectors

Custom Middleware Development

Rotation Middleware

Infinite Scroll and Dynamic Loading

Summary

What’s Next?

Practice Exercise

Scrapy, part 1: fundamentals and your first spider

Scrapy, part 3: staying undetected at scale

Scrapy, part 2: JavaScript, forms, and dynamic pages

Prerequisites

JavaScript, forms, and dynamic pages

What this part covers

JavaScript-Heavy Websites with Scrapy-Splash

Setting Up Splash

Configuring Scrapy for Splash

JavaScript-Enabled Spider

Form Handling and Authentication

Login Spider

Complex Form Handling

AJAX Requests and API Integration

AJAX Spider

Real-time Data Spider

Advanced Selector Techniques

Complex XPath and CSS Selectors

Custom Middleware Development

Rotation Middleware

Infinite Scroll and Dynamic Loading

Summary

What’s Next?

Practice Exercise

Scrapy, part 1: fundamentals and your first spider

Scrapy, part 3: staying undetected at scale