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Version: 3.9

JSDOMCrawler guide

​JSDOMCrawler is very useful for scraping with the Window API.

How the crawler works​

​JSDOMCrawler crawls by making plain HTTP requests to the provided URLs using the specialized got-scraping HTTP client. The URLs are fed to the crawler using RequestQueue. The HTTP responses it gets back are usually HTML pages. The same pages you would get in your browser when you first load a URL. But it can handle any content types with the help of the additionalMimeTypes option.

info

Modern web pages often do not serve all of their content in the first HTML response, but rather the first HTML contains links to other resources such as CSS and JavaScript that get downloaded afterwards, and together they create the final page. To crawl those, see PuppeteerCrawler and PlaywrightCrawler.

Once the page's HTML is retrieved, the crawler will pass it to JSDOM for parsing. The result is a window property, which should be familiar to frontend developers. You can use the Window API to do all sorts of lookups and manipulation of the page's HTML, but in scraping, you will mostly use it to find specific HTML elements and extract their data.

Example use of browser JavaScript:

// Return the page title
document.title; // browsers
window.document.title; // JSDOM

When to use JSDOMCrawler​

JSDOMCrawler really shines when CheerioCrawler is just not enough. There is an entire set of APIs available!

Advantages:

  • Easy to set up
  • Familiar for frontend developers
  • Content can be manipulated
  • Automatically avoids some anti-scraping bans

Disadvantages:

  • Slower than CheerioCrawler
  • Does not work for websites that require JavaScript rendering
  • May easily overload the target website with requests

Example use of Element API​

Find all links on a page​

This snippet finds all <a> elements which have the href attribute and extracts the hrefs into an array.

Array.from(document.querySelectorAll('a[href]')).map((a) => a.href);

Other examples​

Visit the Examples section to browse examples of JSDOMCrawler usage. Almost all examples show JSDOMCrawler code in their code tabs.