Puppeteer vs Selenium: Which is Better for Automation?

Automated testing has become an essential part of modern web development. As web applications grow more complex, manually testing every feature is no longer feasible. Automated testing tools allow developers to write tests that simulate user interactions and verify the application is working as expected.

Two of the most popular tools for automated browser testing are Puppeteer and Selenium. Both can launch a browser, navigate to web pages, interact with elements on a page, and make assertions about page content. However, there are some key differences that make each tool better suited for certain testing scenarios.

In this comprehensive guide, we’ll compare Puppeteer and Selenium to help you determine which is the right choice for your needs.

What is Puppeteer?

Puppeteer is a Node library developed by the Chrome team. It provides a high-level API to control headless Chrome over the DevTools protocol.

Puppeteer runs headless by default, but can be configured to run full (non-headless) Chrome or Chromium.

Some key features of Puppeteer:

• Generates screenshots and PDFs of pages
• Crawls a site to extract content
• Automates form submission, UI testing, keyboard input
• Enables responsive testing by setting device emulation
• Allows execution of browser JavaScript
• API for browser events like navigation and console logs
• Supports extension installation

Puppeteer only supports Chromium-based browsers like Chrome and Microsoft Edge. It does not work with Firefox or Safari.

What is Selenium?

Selenium is an open source suite of tools to automate web browsers. It has been around longer than Puppeteer and has supporters from multiple browser vendors.

Selenium supports multiple languages including Java, C#, Python, JavaScript, and Ruby. It can automate Chrome, Firefox, Edge, and Safari on desktop platforms. Selenium also supports mobile browsers for Android and iOS testing.

Features of Selenium:

• Cross-browser compatibility
• Mobile testing capabilities
• IDE for record and playback
• Grid for distributing tests on multiple machines
• Integrations with various test runners like JUnit, TestNG, Mocha
• Large community of users across industries

Unlike Puppeteer, Selenium does not allow executing browser JavaScript or working directly with DevTools.

Syntax Comparison

Puppeteer uses a concise API that reads like pseudocode. For example:

// Navigate to a URL
await page.goto(‘https://www.example.com‘);

// Get an element 
const button = await page.$(‘#submit-button‘); 

// Click the button  
await button.click();

Selenium uses a more verbose API:

// Launch browser
WebDriver driver = new ChromeDriver();

// Navigate to URL
driver.get("https://www.example.com");

// Find element
WebElement button = driver.findElement(By.id("submit-button"));

// Click element  
button.click(); 

Puppeteer‘s API feels more user-friendly and easier to read. The use of async/await syntax reduces callback nesting. Overall, Puppeteer requires less boilerplate code than Selenium.

Launching Browsers

To launch a browser instance, Puppeteer uses:

const browser = await puppeteer.launch();

With Selenium, you have to initialize a specific driver class:

// Launch Chrome  
WebDriver driver = new ChromeDriver();

// Launch Firefox
WebDriver driver = new FirefoxDriver(); 

Puppeteer only launches Chromium, while Selenium supports multiple browsers. For cross-browser testing, Selenium is a better choice.

Locating Elements

Puppeteer finds elements using:

// Get element by CSS selector
const el = await page.$(‘.className‘);

// Get element by XPath  
const el = await page.$x(‘//xpath‘); 

Selenium locates elements through WebDriver locators:

// Find by CSS
WebElement el = driver.findElement(By.cssSelector(".className"));

// Find by XPath
WebElement el = driver.findElement(By.xpath("//xpath"));

Both tools offer a wide range of locator strategies like ID, class, text, DOM hierarchy. Overall, element selection is straightforward in both.

Interacting with Elements

To interact with elements on a page, Puppeteer uses:

// Type into an input  
await page.type(‘#input‘, ‘Hello world‘);

// Click a button
await button.click(); 

// Select an option
await page.select(‘#dropdown‘, ‘option2‘);

The equivalent Selenium code is:

// Type text  
driver.findElement(By.id("input")).sendKeys("Hello world");

// Click button
button.click();

// Select option
Select dropdown = new Select(driver.findElement(By.id("dropdown")));
dropdown.selectByVisibleText("option2");

Puppeteer‘s API feels more compact and expressive. Selenium requires additional boilerplate for some interactions like selecting dropdowns.

Page Navigation

To navigate to pages, Puppeteer uses:

// Navigate to URL 
await page.goto(‘https://example.com‘);

// Click a link
await page.click(‘a.page2‘); 

// Go back
await page.goBack();

And in Selenium:

// Open URL
driver.get("https://example.com");

// Click link
driver.findElement(By.cssSelector("a.page2")).click();

// Go back  
driver.navigate().back();

Navigation methods are very similar between the two tools. Puppeteer removes some of the verbosity around Selenium‘s nested driver commands.

Executing JavaScript

One major advantage of Puppeteer is the ability to directly execute browser JavaScript:

// Set a cookie 
await page.evaluate(() => {
  document.cookie = "foo=bar"; 
});

// Get an element‘s text 
const text = await page.evaluate(el => el.textContent, element);

Selenium does not provide methods for directly running JavaScript. You have to use workaround techniques like injecting scripts into pages.

Waiting for Elements

Web apps can take time to load content dynamically with JavaScript. Automated tests need to wait for elements to be ready before interacting with them.

Puppeteer makes you manually write waits:

// Wait for selector to be visible
await page.waitForSelector(‘.element‘); 

// Wait for navigation to complete
await page.waitForNavigation();

Selenium has built-in explicit and implicit waits:

// Implicit wait 
driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);

// Explicit wait  
WebDriverWait wait = new WebDriverWait(driver, 10);
wait.until(ExpectedConditions.visibilityOfElementLocated(By.cssSelector(".element")));

Having configurable built-in waits makes it easier to handle timing issues in Selenium. Puppeteer requires manually scripting waits.

Generating Screenshots

Both tools can capture screenshots of pages during testing.

Puppeteer example:

// Take a screenshot 
await page.screenshot({path: ‘page.png‘});

Selenium example:

// Capture screenshot
File screenshot = ((TakesScreenshot)driver).getScreenshotAs(OutputType.FILE);

Screenshot capabilities are very similar. Puppeteer‘s API is a little more straightforward.

Creating PDFs

In addition to screenshots, Puppeteer can generate PDFs of pages:

// Generate PDF
await page.pdf({path: ‘page.pdf‘});

This feature is not built into Selenium. You would need a custom utility to print pages to PDF with Selenium.

Handling Popups

To handle alerts, prompts, and browser popups, Puppeteer provides the page‘s dialog event:

page.on(‘dialog‘, dialog => {
  console.log(dialog.message());
  dialog.accept(); 
});

Selenium uses the Alert interface to interact with popups:

// Switch to alert
Alert alert = driver.switchTo().alert();  

// Get text
String text = alert.getText();

// Accept alert
alert.accept();

Both tools can handle JS popups during automation. Selenium‘s API feels more polished for working with popups.

Parallel Testing

Running tests in parallel can significantly speed up test execution.

Puppeteer does not directly support parallel testing. You have to orchestrate parallel execution through a separate test runner.

Selenium Grid allows distributing tests to run in parallel across multiple machines. This makes it easy to scale Selenium tests.

Browser Logs

Accessing browser logs can be useful for debugging tests and inspecting network activity.

Puppeteer allows capturing the browser console and network logs:

// Listen for console logs
page.on(‘console‘, msg => {
  console.log(‘Page Log:‘, msg.text()); 
}); 

// Get network request logs
const requests = browser.on(‘request‘, request => {
  request.url(); // Log URLs
});

Selenium does not provide methods to directly access browser logs. You would have to find workarounds to get console or network logs.

User-Agent Simulation

Testing how a website responds to different devices and user agents is important.

Puppeteer makes it easy to spoof user agent strings:

await page.setUserAgent(‘Custom User Agent‘);

Selenium does not directly allow setting user agents. This would require configuring browser profiles.

Performance Audits

Puppeteer integrates tools for analyzing page performance:

// Audit performance 
const metrics = await page.audit({
  disableJavaScript: true // Test without JavaScript 
});

// Log metrics
metrics.totalByteWeight; // Total page weight

Performance auditing would require bringing in additional tools with Selenium. Puppeteer builds it right in.

Pricing Comparison

One of the main differences between Puppeteer and Selenium is commercial use restrictions.

Puppeteer is open source and free to use. You can use it commercially without any restrictions.

Selenium is also open source. However, the official Selenium WebDriver binaries are licensed only for non-commercial use. For commercial usage, you need to obtain a license from the Selenium vendor BrowserStack.

This can make Puppeteer preferable for teams that want to use an automation solution commercially without any licensing costs.

Headless Testing

Headless testing refers to running a browser without any visible UI. It provides a lightweight environment for testing.

Puppeteer launches Chrome in headless mode by default, making it ideal for headless testing.

Selenium can also be configured to run headless using options like:

chromeOptions.addArguments("--headless"); 

So both tools allow headless testing, with Puppeteer making it the default out-of-box experience.

Continuous Integration

CI/CD integration is important for automating test execution on code changes.

Puppeteer on its own does not provide any built-in CI/CD capabilities. You need to wire it up to CI tools like Jenkins, CircleCI, etc.

Selenium offers native integration with CI/CD pipelines via selenium-grid. This allows easily distributing tests on CI infrastructure.

Mobile Testing

While both tools focus on web testing, Selenium additionally provides mobile testing support.

The Selenium Appium project enables automating native mobile apps on Android and iOS platforms. Puppeteer does not support mobile app testing.

Learning Curve

For developers familiar with JavaScript and Node.js, Puppeteer is very intuitive to start using. The API design closely mirrors DOM API concepts.

Selenium has a steeper learning curve as you have to learn the Selenium-specific WebDriver API. But Java experience helps ramp up faster.

Overall, Puppeteer is simpler and easier to pick up for those from a web development background.

Debugging Capabilities

Troubleshooting failing tests is an important part of test automation.

Puppeteer allows setting breakpoints and debugging directly in Chrome DevTools for easy debugging:

await page.pause(); // Pause execution

Selenium does not have built-in debugging. You have to rely on log statements or external debugging tools.

Browser Support

The main limitation of Puppeteer is that it only supports Chromium-based browsers. So you cannot use it to test on Firefox or Safari.

Selenium supports Chrome, Firefox, Edge, and Safari enabling true cross-browser testing. If test coverage across browsers is a priority, then Selenium is likely the better choice.

Open-source Community

Selenium has been around for over a decade and has a large community behind it. There are conferences, user groups, and an active Q&A forum dedicated to Selenium.

As a newer project, Puppeteer has a much smaller community. But its developer ergonomics and momentum driven by Google may allow it to catch up over time.

Should You Use Puppeteer or Selenium?

Now that we‘ve compared the two tools, how do you decide whether to use Puppeteer or Selenium?

Here are some key factors to consider:

• Browser support – If you need multi-browser testing, Selenium is the best option. For Chrome-only testing, Puppeteer is a good choice.

• Mobile testing – Selenium supports mobile web and native app testing. Puppeteer is desktop-only.

• Debugging – Puppeteer‘s built-in DevTools integration makes debugging easier.

• Cross-platform – For Java and C# test automation, Selenium has better support. Puppeteer is JS/Node focused.

• Application type – Puppeteer is well suited for testing SPAs and smaller web apps. Selenium scales better for larger enterprise apps with extensive backend integrations.

• Commercial usage – Teams wanting to use automation commercially without licensing limitations can benefit from Puppeteer.

• Programming comfort – For testers coming from a DevOps and JavaScript background, Puppeteer may have a lower learning curve. Java users can ramp up quicker on Selenium.

• Legacy investment – If you already have a substantial number of Selenium tests, it likely makes sense to continue enhancing those rather than starting over with Puppeteer from scratch.

For many test automation needs, both tools can get the job done. Each has unique strengths making it suitable for particular use cases. Hopefully this detailed comparison provides clarity on whether Puppeteer or Selenium is the right choice for your needs.