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CheerioCrawler guide

CheerioCrawler is our simplest and fastest crawler. If you're familiar with jQuery, you'll understand CheerioCrawler in minutes.

What is Cheerio

Cheerio is essentially jQuery for Node.js. It offers the same API, including the familiar $ object. You can use it, as you would use jQuery for manipulating the DOM of an HTML page. In crawling, you'll mostly use it to select the needed elements and extract their values - the data you're interested in. But jQuery runs in a browser and attaches directly to the browser's DOM. Where does cheerio get its HTML? This is where the Crawler part of CheerioCrawler comes in.

How the crawler works

CheerioCrawler 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 Cheerio for parsing. The result is the typical $ function, which should be familiar to jQuery users. You can use the $ function 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 Cheerio and its $ function in comparison to browser JavaScript:

// Return the text content of the <title> element.
document.querySelector('title').textContent; // plain JS
$('title').text(); // Cheerio

// Return an array of all 'href' links on the page.
Array.from(document.querySelectorAll('[href]')).map(el => el.href); // plain JS
$('[href]')
.map((i, el) => $(el).attr('href'))
.get(); // Cheerio
note

This is not to show that Cheerio is better than plain browser JavaScript. Some might actually prefer the more expressive way plain JS provides. Unfortunately, the browser JavaScript methods are not available in Node.js, so Cheerio is your best bet to do the parsing in Node.js.

When to use CheerioCrawler

CheerioCrawler really shines when you need to cope with extremely high workloads. With just 4 GBs of memory and a single CPU core, you can scrape 500 or more pages a minute! (assuming each page contains approximately 400KB of HTML). To scrape this fast with a full browser scraper, such as the PlaywrightCrawler, you'd need significantly more computing power.

Advantages:

  • Extremely fast and cheap to run
  • Easy to set up
  • Familiar for jQuery users
  • Automatically avoids some anti-scraping bans

Disadvantages:

  • Does not work for websites that require JavaScript rendering
  • May easily overload the target website with requests
  • Does not enable any manipulation of the website before scraping

Example use of Cheerio

Get text content of an element

Finds the first <h2> element and returns its text content.

$('h2').text()

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

$('a[href]')
.map((i, el) => $(el).attr('href'))
.get();

Other examples

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