How to use ChromiumLauncher class of PuppeteerSharp package

I found this is the most scalable way to implement this is by using a background process. This is one real-life example:

1. A WebClient request a PDF sending a signalR message.
2. The SignalR hub creates some kind of an ID, put the request in an Azure Queue, and adds the SignalR client to a SignalR group with that ID.
3. A console app would read that queue, process the HTML, and sends back the result to the server using a SignalR message.
4. The WebServer will get the message, and broadcast that message to all the clients in that group.

It might sound quite complicated, but it's not that much. You can make it simpler.

Wait and await - while similar conceptually - are actually completely different.

Wait will synchronously block until the task completes. So the current thread is literally blocked waiting for the task to complete. As a general rule, you should use "async all the way down"; that is, don't block on async code. On my blog, I go into the details of how blocking in asynchronous code causes deadlock.

await will asynchronously wait until the task completes. This means the current method is "paused" (its state is captured) and the method returns an incomplete task to its caller. Later, when the await expression completes, the remainder of the method is scheduled as a continuation.

You also mentioned a "cooperative block", by which I assume you mean a task that you're Waiting on may execute on the waiting thread. There are situations where this can happen, but it's an optimization. There are many situations where it can't happen, like if the task is for another scheduler, or if it's already started or if it's a non-code task (such as in your code example: Wait cannot execute the Delay task inline because there's no code for it).

You may find my async / await intro helpful.

You should be able to do

await page.EvaluateExpressionAsync("window.scrollBy(0, window.innerHeight)");

Adding the stealth plugin to puppeteer-sharp may not be as simple than on the NodeJS Version. A C# port of the puppeteer-extra which works with puppeteersharp exists. Check https://github.com/Overmiind/Puppeteer-sharp-extra.

Either give your submit button an id property and use the #submit selector you previously tried:

<button id="submit" type="submit" class="btn btn-danger btn-lg btn-block">Login</button>

Or use form button[type=submit] as selector.

In Puppeteer, the function that we provide to page.evaluate is executed in context of the page and so it has to be a JavaScript function.

Likewise, in the equivalent functions in puppeteer-sharp e.g. page.EvaluateFunctionAsync, the first argument is a string which is nothing but a JavaScript function. You should be able to use the fetch as it is, something like:

await page.EvaluateFunctionAsync(@"() => {
  return fetch('url', {method: 'POST', body: 'test' });
}");

You can use the Response event:

var page = await browser.NewPageAsync();
page.Response += (sender, e) => 
{
    Console.WriteLine(e.Response.Url);
}

This may be due to CORS.

Try the following code.

var options = new LaunchOptions
{
    Devtools = true,
    Args = new[]
    {
        "--disable-web-security",
        "--disable-features=IsolateOrigins,site-per-process",
    },
};

I solved the problem like this.

const links = await page.evaluate(() =>
              Array.from(document.querySelectorAll('a span'), e => 
              e.textContent));