Question

114

Puppeteer page.evaluate querySelectorAll return empty objects

rated 0 times [ 117] [ 3] / answers: 1 / hits: 46605 / 7 Years ago, sat, september 23, 2017, 12:00:00

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();

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yaquelina

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answered 7 Years ago mickaylag · Accepted Answer

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);