How to Scrape JavaScript Rendered Pages? [2024 Guide]

JavaScript is a popular programming language for creating dynamic web pages. In 2022,98.7% of global websites relied on JavaScript as their preferred client-side programming language.

Scraping data from JavaScript-rendered pages is not an easy task. Unlike static pages, dynamic elements constantly change in real-time. This attribute makes it difficult for automated web scraping because regular tools cannot spot these changes.

Despite the challenges, there are still ways to extract data from JavaScript-rendered pages. Continue reading to discover the steps to scrape data even from the most complex dynamic pages.

🔑 Key Takeaways

• JavaScript-rendered pages present challenges due to varying element load times, shifting website structures, and anti-scraping measures.
• To scrape JavaScript pages, use Headless Browsers, Puppeteer, Selenium WebDriver, Nightmare.js, and Playwright.
• Follow best practices, such as using headless browsers, examining page source code, exploring API endpoints, considering specialized tools like BeautifulSoup, and respecting website policies.
• With the right tools and techniques, scraping JavaScript-rendered pages becomes feasible, thanks to tools like Puppeteer that facilitate efficient data collection.

Scraping JavaScript-Generated Pages 

When scraping data from a JavaScript-generated page, only a portion of the website content is loaded properly. Some JavaScript functions need to be executed to load specific content. 

Scraping a website with JavaScript can be challenging due to two main reasons. These are:

• Anti-Scraping Measures

Rate limiting, IP blocking and CAPTCHAs are anti-scraping measures put in place so website owners can protect their data. These features reduce server load and save website performance. 

• Different Loading Times for Content

Content loads at different times on JavaScript-rendered web pages. As a result, the content you’re looking for has not loaded yet when you try to scrape it.

What You Need to Scrape JavaScript Webpages

Scraping content from JavaScript-based web pages requires specialized tools to interpret the code. JavaScript processing occurs within web browsers after page loading.

These specialized tools are known as Headless Browsers. They act like real browsers but are controlled programmatically.

Here are other tools that you will need to scrape JavaScript-generated pages:

• Puppeteer – a popular tool that comes with high-level API headless Chrome and Chromium browsers that can mimic human interaction with web pages. 
• Selenium WebDriver – a versatile tool for automating browsers. It is your best bet because it supports different programming languages, making it handy for automating many test cases.
• Nightmare.js – a high-level browser automation library that is useful for automated testing jobs like end-to-end testing and browser control.

• Playwright – a web automation tool with a powerful API for browsers. It has a simple and expressive syntax that makes it easy to write and maintain scripts.

6 Steps to Scrape JavaScript-Rendered Pages

In this section, you will learn how to use Puppeteer to scrape a website and save the extracted file.

Step 1: Install Dependencies

Install Node.js on your computer. Open the terminal and navigate to the folder you want to work for your scraping project.

Use this command to install Puppeteer and its necessary components:

npm install puppeteer

Step 2: Create a New File

Create a new JavaScript file using your code editor in the same folder you used in the first step.

Step 3: Write the Scraping Code

In the new JavaScript file, start writing your scraping code. The code below is an example of scraping a website and saving its contents:

const puppeteer =required(‘puppeteer’);

const fs = require(‘fs’);


(async () => {

      const browser = await puppeteer.launch();

      const page = await browser.newPage();

      await page.goto(‘https://www.insert-url.com’);

      const content = await page.content();

      fs.writeFileSync(‘extracted.html’, content);

      await browser.close();

})();

Change “insert-url” to the URL of the website you want to scrape.

Step 4: Save the File

Save your JavaScript file with a “.js” extension.

Step 5: Run the Code

Open your terminal again and navigate to the folder where your JavaScript file is located. Run this command to execute your code:

node your-file-name.js

Step 6: View the Extracted File

Open the extracted file using your browser to see the scraped content. 

Best Practices When Scraping JavaScript Sites

The following are some general tips and tricks for scraping JavaScript web pages:

	Choose a Headless Browser.  Use tools like Puppeteer or Selenium to load and interact with JavaScript on the page.
	Inspect Page Source.  Examine the website’s source code to find the elements you want to scrape.
	Explore API Endpoints.  Check if the websites use external API endpoints to fetch data. You can request data directly from these endpoints.
	Utilize Specialized Tools.  Libraries or tools like BeautifulSoup are designed to handle websites heavy on JavaScript. Consider using them.
	Check Website Policies.  Always read the site’s Terms of Service. Some websites may prohibit scraping, so guarantee you comply before scraping.

Conclusion

Scraping data from JavaScript-rendered pages means dealing with changing structures and anti-scraping measures. However, with the right tools and techniques, data extraction becomes possible.

Tools like Puppeteer, Selenium, Nightmare.js, and Playwright are vital for automating JavaScript-based web scraping. Using headless browsers, inspecting page sources, and exploring API  endpoints enable efficient data collection.

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By Harsha Kiran

Harsha Kiran is the founder and innovator of Techjury.net. He started it as a personal passion project in 2019 to share expertise in internet marketing and experiences with gadgets and it soon turned into a full-scale tech blog with specialization in security, privacy, web dev, and cloud computing.