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document.getElementsByTagName returns object tree with empty values? #1263

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document.getElementsByTagName returns object tree with empty values?#1263
@webchaz

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@webchaz
webchaz
opened on Nov 2, 2017

I have the following code:

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto('https://www.amazon.com');

  const a = await page.evaluate(() => {
    return document.getElementsByTagName('a')
  });
  console.log(a)
})();

This results in a long list of:

{
  '0': {},
  '1': {},
  '2': {},
  '3': { jQuery16409950154717072515: 199 },
  '4': { jQuery16409950154717072515: 191 },
  '5': {}
}

How do I get the actual DOM from this?

Activity

ebidel

ebidel commented on Nov 2, 2017

@ebidel
ebidel
on Nov 2, 2017 · edited by ebidel
Contributor

You can't return the actual page DOM back into a puppeteer script. Those objects live in separate worlds. What you get from page.evaluate() is a JSONHandle that you can actual on. By default, this gets serialized (if it can be). So that's what you're seeing.

jsonValue() and getProperties() are useful for acting on the return object. For example, if you wanted to get all of the hrefs:

const list = await page.evaluateHandle(() => {
  return Array.from(document.getElementsByTagName('a')).map(a => a.href);
});
console.log(await list.jsonValue());

What are you trying to do?

ernstbolt

ernstbolt commented on Dec 15, 2017

@ernstbolt
ernstbolt
on Dec 15, 2017 · edited by ernstbolt

Thank you! Just what I was looking for!

aslushnikov
closed this as completedon Jan 12, 2018
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          document.getElementsByTagName returns object tree with empty values? · Issue #1263 · puppeteer/puppeteer