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Browser console and Puppeteer cannot find certain selector

I am trying to build a simple scraper for this website by using puppeteer.
The code goes as follows:
const browser = await puppeteer.launch({
headless: false
});
const page = await browser.newPage();
let pagelink = "https://www.speisekarte.de/berlin/restaurants?page=1"
await page.waitFor(3 * 1000);
await page.goto(pagelink);
await page.waitFor(3 * 1000);
await page.waitForSelector("#notice")
However, I cannot access the overlay notice for the cookies which should have the Id "notice".
This does not work either for await page.waitForSelector("#notice")
in my puppeteer code.
Nor with document.getElementById("notice") in Chromium, if I use the console of Chromium during the session manually. Also, it does not work, if I use it in Firefox's console. Funnily enough, chunks like
document.querySelectorAll("button")
work as expected. I checked with a colleague and she can access the element using the above mentioned queries in her Chrome and in her Firefox browser. She also uses a Mac. Any idea, what is happening here? Any help would be much appreciated.

why puppeteer does not type in some inputs

Somtimes puppeteer does not type in some input fields, to be specific, I tried to simply type something in a website's input filed called "https://webtor.io/", which has a single huge input field, I hope someone could help me with that specific example.
const puppeteer = require('puppeteer');
(async () => {
const browser = await puppeteer.launch({ headless: false });
const page = await browser.newPage();
await page.goto('https://webtor.io/');
await page.type(`input[type="text"]`, 'something', { delay: 50 })
})();

This happens because when you go to the page the page has render the html and load up scripts, which ends up causing the delay and sometimes the text input is not loaded hence the fail.
await page.goto(''https://webtor.io/', {waitUntil: 'networkidle0'});
Check out this link for further details.
Puppeteer wait until page is completely loaded

Puppeteer and Playwright chrome headful bugs when making a screenshot

I am currently developing a node.js script that needs to launch a headful chromium instance using Puppeteer and then make a screenshot of a page every 3 seconds, this is my code :
const puppeteer = require('puppeteer');
async function init (){
const browser = await puppeteer.launch({headless: true});
const page = await browser.newPage();
await page.goto('https://example.com');
screenshot(page)
};
async function screenshot(page){
let buffer = await page.screenshot();
let imageBuffer = buffer.toString('base64');
// save imageBuffer to database
setTimeout(screenshot, 3000, page)
}
My current issue is that I need the user to still be able to normally navigate on the browser and on his computer but this impossible as :
The page lags when making the screenshot as you can see on the following video : https://youtu.be/Tl2w-qKckkc
The browser window focuses and goes on top of all the windows when making the screenshot.
I also tried using Playwright but the same bug occurs when using it with chromium. Can someone please help.

In Playwright, do the following:
// Affects all the platforms.
const page = await browser.newPage({ viewport: null });
// Local fix for those using Apple hardware with Retina displays.
const page = await browser.newPage({ deviceScaleFactor: 2 });
I posted a detailed reply at https://github.com/microsoft/playwright/issues/2576. Please feel free to follow up and ask questions / request features there!

How to know the chromium path used by puppeteer?

I installed puppeteer on my debian server, and I'm trying to use it through php :
print shell_exec("node pptscript.js");
pptscript.js:
const puppeteer = require('puppeteer');
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto('https://www.google.com');
await page.screenshot({path: '/var/www/web/example.png'});
await browser.close();
})();
But it doesn't work and I have no output.
I read somewhere that chmoding to 777 the chromium executable can solve the problem because user www-data have no right to execute it. But I don't know where is it.

browser has an internal function called process() which returns a ChildProcess. You can read the spawnfile property of that ChildProcess.
console.log(browser.process().spawnfile);

Can the browser turned headless mid-execution when it was started normally, or vice-versa?

I want to start a chromium browser instant headless, do some automated operations, and then turn it visible before doing the rest of the stuff.
Is this possible to do using Puppeteer, and if it is, can you tell me how? And if it is not, is there any other framework or library for browser automation that can do this?
So far I've tried the following but it didn't work.
const browser = await puppeteer.launch({'headless': false});
browser.headless = true;
const page = await browser.newPage();
await page.goto('https://news.ycombinator.com', {waitUntil: 'networkidle2'});
await page.pdf({path: 'hn.pdf', format: 'A4'});

Short answer: It's not possible
Chrome only allows to either start the browser in headless or non-headless mode. You have to specify it when you launch the browser and it is not possible to switch during runtime.
What is possible, is to launch a second browser and reuse cookies (and any other data) from the first browser.
Long answer
You would assume that you could just reuse the data directory when calling puppeteer.launch, but this is currently not possible due to multiple bugs (#1268, #1270 in the puppeteer repo).
So the best approach is to save any cookies or local storage data that you need to share between the browser instances and restore the data when you launch the browser. You then visit the website a second time. Be aware that any state the website has in terms of JavaScript variable, will be lost when you recrawl the page.
Process
Summing up, the whole process should look like this (or vice versa for headless to headfull):
Crawl in non-headless mode until you want to switch mode
Serialize cookies
Launch or reuse second browser (in headless mode)
Restore cookies
Revisit page
Continue crawling

As mentioned, this isn't currently possible since the headless switch occurs via Chromium launch flags.
I usually do this with userDataDir, which the Chromium docs describe as follows:
The user data directory contains profile data such as history, bookmarks, and cookies, as well as other per-installation local state.
Here's a simple example. This launches a browser headlessly, sets a local storage value on an arbitrary page, closes the browser, re-opens it headfully, retrieves the local storage value and prints it.
const puppeteer = require("puppeteer"); // ^18.0.4
const url = "https://www.example.com";
const opts = {userDataDir: "./data"};
let browser;
(async () => {
{
browser = await puppeteer.launch({...opts, headless: true});
const [page] = await browser.pages();
await page.goto(url, {waitUntil: "domcontentloaded"});
await page.evaluate(() => localStorage.setItem("hello", "world"));
await browser.close();
}
{
browser = await puppeteer.launch({...opts, headless: false});
const [page] = await browser.pages();
await page.goto(url, {waitUntil: "domcontentloaded"});
const result = await page.evaluate(() => localStorage.getItem("hello"));
console.log(result); // => world
}
})()
.catch(err => console.error(err))
.finally(() => browser?.close())
;
Change const opts = {userDataDir: "./data"}; to const opts = {}; and you'll see null print instead of world; the user data doesn't persist.
The answer from a few years ago mentions issues with userDataDir and suggests a cookies solution. That's fine, but I haven't had any issues with userDataDir so either they've been resolved on the Puppeteer end or my use cases haven't triggered the issues.
There's a useful-looking answer from a reputable source in How to turn headless on after launch? but I haven't had a chance to try it yet.