How to specify browser language in Puppeteer

2 min read 06-10-2024

How to specify browser language in Puppeteer

Navigating the Web with Puppeteer: Setting Your Browser's Language Preferences

Puppeteer, the powerful Node.js library for controlling Chrome or Chromium, offers a versatile way to automate web browsing tasks. But what if you need to simulate a specific user experience with a certain language preference? This is where setting the browser's language comes in.

The Problem: A Globalized Web

Imagine you're developing a website that needs to cater to users from different regions. You want to test how your website renders in different languages. This is where Puppeteer's language setting capabilities come in handy.

Setting the Stage: Code and Scenario

Let's say you want to test a website in French. Here's how you could use Puppeteer to simulate a French user experience:

const puppeteer = require('puppeteer');

async function browseInFrench() {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();

  // Set the browser's language to French
  await page.setExtraHTTPHeaders({
    'Accept-Language': 'fr-FR'
  });

  await page.goto('https://example.com');

  // Your tests or actions go here
  await page.screenshot({ path: 'example.png' });

  await browser.close();
}

browseInFrench();

Breaking it Down: Understanding the Code

Import Puppeteer: This line imports the Puppeteer library, the backbone of our browser automation.
Launch Browser: puppeteer.launch() creates a new Chromium instance.
New Page: browser.newPage() creates a new tab within the browser.
Set Language: The page.setExtraHTTPHeaders() method is key. It allows you to set custom HTTP headers, including the crucial Accept-Language header. In this case, we set it to fr-FR, indicating a preference for French (France).
Navigation: page.goto() loads the website.
Your Tests: Here you would place your actions, such as taking screenshots, interacting with elements, or asserting specific behavior based on the French language setting.
Cleanup: browser.close() shuts down the browser instance.

Key Considerations:

Language Codes: The Accept-Language header accepts a list of language codes in decreasing order of preference. Use https://en.wikipedia.org/wiki/IETF_language_tag for an extensive list of language codes.
Browser Response: Websites may not always honor the Accept-Language header. It's a signal, not a guarantee.
Localization: Consider the nuances of localization. Different language versions of a website may have structural differences, including the placement of elements, the order of content, and even the availability of certain features.

Expanding Your Horizons: Additional Tips

User Agent: Customize the user agent to simulate a specific browser, operating system, and device, further enhancing the accuracy of your language testing.
Cookies: Set cookies relevant to the target language to personalize the experience.
Geolocation: Combine language settings with simulated geolocation to mimic a user's complete location and preferences.

By mastering the art of browser language control with Puppeteer, you can unlock a world of possibilities for testing, scraping, and automating tasks in a multilingual web environment.