Puppeteer: Why Does the Selector Evaluation Return an Empty Object?

Other Questions Puppeteer
1

When using Puppeteer’s element selector, the returned object is empty rather than a full DOM node. How can I access the complete element?

const puppLib = require('puppeteer');

(async () => {
  const browserInst = await puppLib.launch({ headless: false, slowMo: 500 });
  const currentPage = await browserInst.newPage();
  await currentPage.goto('https://example.com');

  const elementText = await currentPage.$eval('#mainSection', el => el.innerText);
  console.log('Element Text:', elementText);

  const completeElement = await currentPage.$eval('#mainSection', el => el);
  console.log('Complete Element:', completeElement); // Expected a DOM node

  await browserInst.close();
})();
2

hey, keep in mind that dom nodes cant be serialized to node. u only get a copy of what you return in page context. try returning outerhtml or specific props. its a limitation in pupp’s cross context work, not really an error.

3

The empty object is the result of Puppeteer serializing what is returned from the browser context rather than transferring a live DOM node back to Node. In my experience, this happens because a full DOM node isn’t serializable, and only plain data can cross the context barrier. Instead of returning the DOM node directly, I extract the necessary properties like innerHTML or outerHTML. This approach avoids the limitation imposed by the cross-context communication and fits within Puppeteer’s design.

4

I encountered this exact issue when I started using Puppeteer for a project. My confusion began when I tried to return a direct DOM element, only to see an empty object because Puppeteer serializes only plain data. Through trial and error, I discovered that the correct approach is to extract only the details you need, like innerHTML, outerHTML, or specific attributes. While it might seem limiting, this design ensures that the browser and Node environments remain separate and avoids potential issues with live DOM manipulations on the server.

5

The behavior is expected. Puppeteer’s $eval returns the result of the function executed within the browser context, and DOM nodes are not serializable when transferred back to Node.js. In my own work, I found that if you need access to properties of an element, it’s better to extract and return those properties such as outerHTML, attributes, or any specific details within the page context. This way, your code is not expecting a complete DOM node in Node.js but rather the information extracted from it. It’s a design choice to keep the context boundaries clear.