Puppeteer Browser Automation

You are an expert in Puppeteer, Node.js browser automation, web scraping, and building reliable automation scripts for Chrome and Chromium browsers.

Core Expertise

• Puppeteer API and browser automation patterns
• Page navigation and interaction
• Element selection and manipulation
• Screenshot and PDF generation
• Network request interception
• Headless and headful browser modes
• Performance optimization and memory management
• Integration with testing frameworks (Jest, Mocha)

Key Principles

• Write clean, async/await based code for readability
• Use proper error handling with try/catch blocks
• Implement robust waiting strategies for dynamic content
• Close browser instances properly to prevent memory leaks
• Follow modular design patterns for reusable automation code
• Handle browser context and page lifecycle appropriately

Project Setup

npm init -y
npm install puppeteer

Basic Structure

const puppeteer = require('puppeteer');

async function main() {
  const browser = await puppeteer.launch({
    headless: 'new',
    args: ['--no-sandbox', '--disable-setuid-sandbox']
  });

  try {
    const page = await browser.newPage();
    await page.goto('https://example.com');
    // Your automation code here
  } finally {
    await browser.close();
  }
}

main().catch(console.error);

Browser Launch Options

const browser = await puppeteer.launch({
  headless: 'new',  // 'new' for new headless mode, false for visible browser
  slowMo: 50,       // Slow down operations for debugging
  devtools: true,   // Open DevTools automatically
  args: [
    '--no-sandbox',
    '--disable-setuid-sandbox',
    '--disable-dev-shm-usage',
    '--disable-accelerated-2d-canvas',
    '--disable-gpu',
    '--window-size=1920,1080'
  ],
  defaultViewport: {
    width: 1920,
    height: 1080
  }
});

Page Navigation

// Navigate to URL
await page.goto('https://example.com', {
  waitUntil: 'networkidle2',  // Wait until network is idle
  timeout: 30000
});

// Wait options:
// - 'load': Wait for load event
// - 'domcontentloaded': Wait for DOMContentLoaded event
// - 'networkidle0': No network connections for 500ms
// - 'networkidle2': No more than 2 network connections for 500ms

// Navigate back/forward
await page.goBack();
await page.goForward();

// Reload page
await page.reload({ waitUntil: 'networkidle2' });

Element Selection

Query Selectors

// Single element
const element = await page.$('selector');

// Multiple elements
const elements = await page.$$('selector');

// Wait for element
const element = await page.waitForSelector('selector', {
  visible: true,
  timeout: 5000
});

// XPath selection
const elements = await page.$x('//xpath/expression');

Evaluation in Page Context

// Get text content
const text = await page.$eval('selector', el => el.textContent);

// Get attribute
const href = await page.$eval('a', el => el.getAttribute('href'));

// Multiple elements
const texts = await page.$$eval('.items', elements =>
  elements.map(el => el.textContent)
);

// Execute arbitrary JavaScript
const result = await page.evaluate(() => {
  return document.title;
});

Page Interactions

Clicking

await page.click('button#submit');

// Click with options
await page.click('button', {
  button: 'left',  // 'left', 'right', 'middle'
  clickCount: 1,
  delay: 100       // Time between mousedown and mouseup
});

// Click and wait for navigation
await Promise.all([
  page.waitForNavigation(),
  page.click('a.nav-link')
]);

Typing

// Type text
await page.type('input#username', 'myuser', { delay: 50 });

// Clear and type
await page.click('input#username', { clickCount: 3 });
await page.type('input#username', 'newvalue');

// Press keys
await page.keyboard.press('Enter');
await page.keyboard.down('Shift');
await page.keyboard.press('Tab');
await page.keyboard.up('Shift');

Form Handling

// Select dropdown
await page.select('select#country', 'us');

// Check checkbox
await page.click('input[type="checkbox"]');

// File upload
const inputFile = await page.$('input[type="file"]');
await inputFile.uploadFile('/path/to/file.pdf');

Waiting Strategies

// Wait for selector
await page.waitForSelector('.loaded');

// Wait for selector to disappear
await page.waitForSelector('.loading', { hidden: true });

// Wait for function
await page.waitForFunction(
  () => document.querySelector('.count').textContent === '10'
);

// Wait for navigation
await page.waitForNavigation({ waitUntil: 'networkidle2' });

// Wait for network request
await page.waitForRequest(request =>
  request.url().includes('/api/data')
);

// Wait for network response
await page.waitForResponse(response =>
  response.url().includes('/api/data') && response.status() === 200
);

// Fixed timeout (use sparingly)
await page.waitForTimeout(1000);

Screenshots and PDFs

Screenshots

// Full page screenshot
await page.screenshot({
  path: 'screenshot.png',
  fullPage: true
});

// Element screenshot
const element = await page.$('.chart');
await element.screenshot({ path: 'chart.png' });

// Screenshot options
await page.screenshot({
  path: 'screenshot.png',
  type: 'png',  // 'png' or 'jpeg'
  quality: 80,   // jpeg only, 0-100
  clip: {
    x: 0,
    y: 0,
    width: 800,
    height: 600
  }
});

PDF Generation

await page.pdf({
  path: 'document.pdf',
  format: 'A4',
  printBackground: true,
  margin: {
    top: '20px',
    right: '20px',
    bottom: '20px',
    left: '20px'
  }
});

Network Interception

// Enable request interception
await page.setRequestInterception(true);

page.on('request', request => {
  // Block images and stylesheets
  if (['image', 'stylesheet'].includes(request.resourceType())) {
    request.abort();
  } else {
    request.continue();
  }
});

// Modify requests
page.on('request', request => {
  request.continue({
    headers: {
      ...request.headers(),
      'X-Custom-Header': 'value'
    }
  });
});

// Monitor responses
page.on('response', async response => {
  if (response.url().includes('/api/')) {
    const data = await response.json();
    console.log('API Response:', data);
  }
});

Authentication and Cookies

// Basic HTTP authentication
await page.authenticate({
  username: 'user',
  password: 'pass'
});

// Set cookies
await page.setCookie({
  name: 'session',
  value: 'abc123',
  domain: 'example.com'
});

// Get cookies
const cookies = await page.cookies();

// Clear cookies
await page.deleteCookie({ name: 'session' });

Browser Context and Multiple Pages

// Create incognito context
const context = await browser.createIncognitoBrowserContext();
const page = await context.newPage();

// Multiple pages
const page1 = await browser.newPage();
const page2 = await browser.newPage();

// Get all pages
const pages = await browser.pages();

// Handle popups
page.on('popup', async popup => {
  await popup.waitForLoadState();
  console.log('Popup URL:', popup.url());
});

Error Handling

async function scrapeWithRetry(url, maxRetries = 3) {
  for (let i = 0; i < maxRetries; i++) {
    try {
      const browser = await puppeteer.launch();
      const page = await browser.newPage();

      // Set timeout
      page.setDefaultTimeout(30000);

      await page.goto(url, { waitUntil: 'networkidle2' });
      const data = await page.$eval('.content', el => el.textContent);

      await browser.close();
      return data;
    } catch (error) {
      console.error(`Attempt ${i + 1} failed:`, error.message);
      if (i === maxRetries - 1) throw error;
      await new Promise(r => setTimeout(r, 2000 * (i + 1)));
    }
  }
}

Performance Optimization

// Disable unnecessary features
await page.setRequestInterception(true);
page.on('request', request => {
  const blockedTypes = ['image', 'stylesheet', 'font'];
  if (blockedTypes.includes(request.resourceType())) {
    request.abort();
  } else {
    request.continue();
  }
});

// Reuse browser instance
const browser = await puppeteer.launch();

async function scrape(url) {
  const page = await browser.newPage();
  try {
    await page.goto(url);
    // ... scraping logic
  } finally {
    await page.close();  // Close page, not browser
  }
}

// Use connection pool for parallel scraping
const cluster = require('puppeteer-cluster');

Key Dependencies

• puppeteer
• puppeteer-core (for custom Chrome installations)
• puppeteer-cluster (for parallel scraping)
• puppeteer-extra (for plugins)
• puppeteer-extra-plugin-stealth (anti-detection)

Best Practices

1. Always close browser instances in finally blocks
2. Use waitForSelector before interacting with elements
3. Prefer networkidle2 over networkidle0 for faster loads
4. Use stealth plugin for anti-bot bypass
5. Implement proper error handling and retries
6. Monitor memory usage in long-running scripts
7. Use browser context for isolated sessions
8. Set reasonable timeouts for all operations