How to Extract Data with a Headless Browser?

Ecommerce 27.03.2023

The automated scraping process is necessary for getting the competitor site’s information to improve the structure of your website, developing new efficient product characteristics, getting the user’s data, etc. HTML and regex methods are popular nowadays and widely used by specialists. However, the alternative algorithms using browsers without the graphical user interface have grown in popularity. So, let’s understand the features of such a strategy and determine if it can replace writing traditional parsers.

What is a Headless Browser? 

Before speaking about scraping, let’s determine the standard features of a well-known web browser. Simply put, it is a software element representing a web page for its review on the screen. It makes the code from the server become visual information on the monitor – text, pictures, animations, etc. Moreover, it allows various interactive functions by clicking on the specific elements. But, all the necessary visualization procedures (rendering) are provided with the PC, and the browser firstly asks for a raw HTML code. After that, it gives additional requests to the server to represent the final image on the screen. 

However, many modern new websites are not based only on CSS and HTML – they have many additional opportunities and API integrations that make users admire their multifunctional design. The innovative sites include the code for analytics, social media, tracking, etc. Those are the features of the creative web solutions helping site owners correspond to modern marketing requirements. 

Therefore, when speaking about scraping, the comprehensive information to extract can usually be in the non-processed part of the HTML code of the web page. So, the data can be acquired only when the code (for instance, JavaScript) processes it with the help of an exceptionally maintained browser. So, such a browser is named headless because it isn’t controlled by a non-human operator – a preliminary written code that determines all the operations for getting the necessary information. 

What Opportunities does Such a Scraping Method Provide? 

The most popular headless browser is Chrome, based on the similar Google application typically used with a multifunctional library – Puppeteer. 

Pros of Working with Chrome

Such a browser has the following advantages for data mining: 

  • DOM and JavaScript rendering.
  • Interaction with the design elements:
    • Filling in the necessary forms. 
    • Link transactions. 
    • Drag&Drop.
    • Uploading files of various formats.
    • Computer mouse emulation. 
  • Simple overcoming of the parsing obstacles such as bot traps, captchas, etc.
  • Saving resources while running a browser on servers without a graphical environment.

However, when providing web crawling, it’s necessary to remember that browser work is much more demanding on the PC performance and its RAM and CPU characteristics. Depending on the complexity of the site, it is recommended to use no more than 1-2 threads for each processor core. For example, you should use 8 to 16 tabs for the 8-core processor. 

Pros of Scraping with Puppeteer

The library provides particular benefits: 

  • support for separate proxies for each browser tab;
  • multi-threaded browser tab management;
  • interception of requests. 

The library provides efficient control of the Chromium headless browser and allows its easy use for getting the data. 

Methods for Puppeteer

Here, you can see the required methods used for the web crawling code with Chromium: 

  • await this.puppeteer.launch: it is similar to the .launch method, starting the Chromium browser with the required settings. The method includes additional options:
    • logConnections: boolean: it enables logging of all connections (regardless of using a proxy or not), and the output of the log is carried out separately by streams. 
    • stealth: boolean:  the method uses the puppeteer-extra plugin to disguise Chromium as real Chrome. 
    • stealthOpts: any Additional options for the puppeteer-extra plugin. 
  • await this.puppeteer.setPageUseProxy (page): this method binds the browser page to the parser thread for the proxy to work correctly (must be called immediately after the page is created). 
  • await this.puppeteer.closeActiveConnections(page): it must be implemented after completing the request processing or before changing the proxy to process the next request attempt. 

The listed methods should be used for web scraping and provide good work of the code for the Chromium browser. 

To Sum Up 

Overall, using headless browsers for getting data from websites is efficient and widely used nowadays. However, its efficient implementation requires advanced programming knowledge and should be provided by experienced specialists to minimize the risk of improper browser work.