javascript - Puppeteer page.evaluate querySelectorAll return empty objects

Question

I am trying out Puppeteer. This is a sample code that you can run on: https://try-puppeteer.appspot.com/

The problem is this code is returning an array of empty objects:

[{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{}]

Am I making a mistake?

const browser = await puppeteer.launch();

const page = await browser.newPage();
await page.goto('https://reddit.com/');

let list = await page.evaluate(() => {
  return Promise.resolve(Array.from(document.querySelectorAll('.title')));
});

console.log(JSON.stringify(list))

await browser.close();

Answer 1

The values returned from evaluate function should be json serializeable. https://github.com/GoogleChrome/puppeteer/issues/303#issuecomment-322919968

the solution is to extract the href values from the elements and return it.

 await this.page.evaluate((sel) => {
        let elements = Array.from(document.querySelectorAll(sel));
        let links = elements.map(element => {
            return element.href
        })
        return links;
    }, sel);