jsdomvschompjs
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.
chompjs can be used in web scrapping for turning JavaScript objects embedded in pages into valid Python dictionaries.
In web scraping this is particularly useful for parsing Javascript variables like:
python
import chompjs
js = """
var myObj = {
myMethod: function(params) {
// ...
},
myValue: 100
}
"""
chompjs.parse_js_object(js, json_params={'strict': False})
{'myMethod': 'function(params) {\n // ...\n }', 'myValue': 100}
In practice this can be used to extract hidden JSON data like data from <script id=__NEXT_DATA__> elements
from nextjs (and similar) websites. Unlike json.loads command chompjs can ingest json documents that contain
javascript natives like functions making it a super easy way to scrape hidden web data objects.
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); }); ```
```python
basic use
import chompjs js = """ var myObj = { myMethod: function(params) { // ... }, myValue: 100 } """ chompjs.parse_js_object(js, json_params={'strict': False}) {'myMethod': 'function(params) {\n // ...\n }', 'myValue': 100}
example how to use with hidden data parsing:
import httpx import chompjs from parsel import Selector
response = httpx.get("http://example.com") hidden_script = Selector(response.text).css("script#NEXT_DATA::text").get() data = chompjs.parse_js_object(hidden_script) print(data['props']) ```