jsdomvsrvest
jsdom is a pure JavaScript implementation of web standards, notably the WHATWG DOM and HTML standards, for use with Node.js. It simulates a browser environment in Node.js, allowing you to parse HTML, manipulate the DOM, and interact with web pages using the same APIs available in web browsers.
Key features for web scraping:
- Full DOM implementation Provides document.querySelector, document.querySelectorAll, and other standard DOM methods for traversing and manipulating parsed HTML.
- Browser-like environment Simulates window, document, navigator, and other browser globals, enabling code that was written for browsers to run in Node.js.
- JavaScript execution Can execute JavaScript embedded in HTML pages, including external scripts, making it possible to process pages that generate content dynamically (though much slower than a real browser).
- Standards-compliant parsing Uses the same HTML parsing algorithm as web browsers (the WHATWG HTML specification), ensuring accurate handling of malformed HTML.
- Cookie support Implements the tough-cookie library for cookie handling across requests.
For web scraping, jsdom is useful when you need more than simple CSS selector matching (what cheerio provides) but don't need a full browser. It's ideal for parsing complex HTML and running simple inline scripts without the overhead of Playwright or Puppeteer. However, for heavy JavaScript-rendered pages, a real browser automation tool is recommended.
rvest is a popular R library for web scraping and parsing HTML and XML documents. It is built on top of the xml2 and httr libraries and provides a simple and consistent API for interacting with web pages.
One of the main advantages of using rvest is its simplicity and ease of use. It provides a number of functions that make it easy to extract information from web pages, even for those who are not familiar with web scraping. The html_nodes and html_node functions allow you to select elements from an HTML document using CSS selectors, similar to how you would select elements in JavaScript.
rvest also provides functions for interacting with forms, including html_form, set_values, and submit_form functions. These functions make it easy to navigate through forms and submit data to the server, which can be useful when scraping sites that require authentication or when interacting with dynamic web pages.
rvest also provides functions for parsing XML documents. It includes xml_nodes and xml_node functions, which also use CSS selectors to select elements from an XML document, as well as xml_attrs and xml_attr functions to extract attributes from elements.
Another advantage of rvest is that it provides a way to handle cookies, so you can keep the session alive while scraping a website, and also you can handle redirections with handle_redirects
Highlights
Example Use
Product A
$10.99Product B
$24.99
</body>
`;
const dom = new JSDOM(html); const document = dom.window.document;
// Use standard DOM APIs to extract data
const products = document.querySelectorAll('.product');
products.forEach(product => {
const name = product.querySelector('h2').textContent;
const price = product.querySelector('.price').textContent;
console.log(${name}: ${price});
});
// Fetch and parse a remote page JSDOM.fromURL('https://example.com').then(dom => { const title = dom.window.document.title; console.log('Page title:', title); }); ```
```r library("rvest")
Rvest can use basic HTTP client to download remote HTML:
tree <- read_html("http://webscraping.fyi/lib/r/rvest")
or read from string:
tree <- read_html('
')
to parse HTML trees with rvest we use r pipes (the %>% symbol) and html_element function:
we can use css selectors:
print(tree %>% html_element(".products>a") %>% html_text())
"[1] "\nCat Food\nDog Food\n""
or XPath:
print(tree %>% html_element(xpath="//div[@class='products']/a") %>% html_text())
"[1] "\nCat Food\nDog Food\n""
Additionally rvest offers many quality of life functions:
html_text2 - removes trailing and leading spaces and joins values
print(tree %>% html_element("div") %>% html_text2())
"[1] "Cat Food Dog Food""
html_attr - selects element's attribute:
print(tree %>% html_element("div") %>% html_attr('class'))
"products"
```