You could use a using block for that:

public static async Task<string> renderHtmlAsync(string url2)
{
    await new BrowserFetcher().DownloadAsync(BrowserFetcher.DefaultChromiumRevision);
    using (Browser browser = await Puppeteer.LaunchAsync(new LaunchOptions
    {
        Headless = true
    }))
    {
        var page = await browser.NewPageAsync();
        page.DefaultTimeout = 0;
        var navigation = new NavigationOptions
        {
            Timeout = 0,
            WaitUntil = new[] {
                    WaitUntilNavigation.DOMContentLoaded }
        };
        await page.GoToAsync(url2, navigation);
        var content = page.GetContentAsync();

        return await content;
    }
}

This works like:

var myObject = new DispoableObject();
try
{
    // insert code
    return result;
}
finally
{
    myObject.Dispose();
}

The code in the finally is always executed, even when an exception is thrown inside the try block.

We cannot convert the whole code for you but here are some pointers. You need to take one chunk of problem at a time.

Break the while loop

Let us look into the JS code,

let count = 0;
while (await page.$('#search-content button.btn-icon') !== null && count != 1) {}

It's creating a while look, which stops if count is 1.

Now your C# Code,

while (await page.QuerySelectorAsync("#search-content button.btn-icon") != null)

It's not checking for count, this will end up in infinite while loop.

You should count the number,

int count = 0;
while (await page.QuerySelectorAsync("#search-content button.btn-icon") != null && count != 1){
 // other code
 count++;
}

This way it will stop after it finds one result.

Learn more about Promise.all etc.

Your rest of the question is about Promise.all and few other stuff. Here are some useful links,

• Promise.all()
• API Documentation for Puppeteer Sharp
• API Documentation for Puppeteer

SetExtraHttpHeadersAsync expects a dictionary with the headers to append:

await Page.SetExtraHttpHeadersAsync(new Dictionary<string, string>
{
  ["Referer"] = "Bar"
});

For anybody still encountering this issue, the answer by jamie-tillman on this github issue solved it for me:

FROM mcr.microsoft.com/dotnet/aspnet:6.0 AS base
#####################
#PUPPETEER RECIPE based on https://github.com/hardkoded/puppeteer-sharp/issues/1180#issuecomment-1015532968
#####################
RUN apt-get update && apt-get -f install && apt-get -y install wget gnupg2 apt-utils
RUN wget -q -O - https://dl.google.com/linux/linux_signing_key.pub | apt-key add -
RUN echo 'deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main' >> /etc/apt/sources.list
RUN apt-get update \
&& apt-get install -y google-chrome-stable --no-install-recommends --allow-downgrades fonts-ipafont-gothic fonts-wqy-zenhei fonts-thai-tlwg fonts-kacst fonts-freefont-ttf
######################
#END PUPPETEER RECIPE
######################
ENV PUPPETEER_EXECUTABLE_PATH "/usr/bin/google-chrome-stable"
WORKDIR /app
EXPOSE 80
EXPOSE 443

The path to the executable is automatically detected by Puppeteer. However, I still had to disable sandboxmode as seen in the snippet below:

var browser = await Puppeteer.LaunchAsync(new LaunchOptions
{
    Headless = true,
    Args = new [] {
      "--disable-gpu",
      "--disable-dev-shm-usage",
      "--disable-setuid-sandbox",
      "--no-sandbox"}
});

More useful information is found in the issue thread so I recommend skimming through it if you still have trouble.

That's the right way, for example:

var six = await page.EvaluateFunctionAsync<int>("async () => await Promise.resolve(6)");

PuppeteerSharp doesn't have those APIs (because Pupppeteer doesn't have them). But, you could try sending those messages to the browser in the same way TapAsync does.

This is the TapAsync code:

// Touches appear to be lost during the first frame after navigation.
// This waits a frame before sending the tap.
// @see https://crbug.com/613219
await _client.SendAsync("Runtime.evaluate", new RuntimeEvaluateRequest
{
    Expression = "new Promise(x => requestAnimationFrame(() => requestAnimationFrame(x)))",
    AwaitPromise = true
}).ConfigureAwait(false);

var touchPoints = new[] { new TouchPoint { X = Math.Round(x), Y = Math.Round(y) } };
await _client.SendAsync("Input.dispatchTouchEvent", new InputDispatchTouchEventRequest
{
    Type = "touchStart",
    TouchPoints = touchPoints,
    Modifiers = _keyboard.Modifiers
}).ConfigureAwait(false);

await _client.SendAsync("Input.dispatchTouchEvent", new InputDispatchTouchEventRequest
{
    Type = "touchEnd",
    TouchPoints = Array.Empty<TouchPoint>(),
    Modifiers = _keyboard.Modifiers
}).ConfigureAwait(false);

Page has a public property Client. You can use that Client to perform these calls.

As you can check here, Type supports: touchStart, touchEnd, touchMove and touchCancel.

You have to keep in mind that there is browser behind. A Page instance won't be as resource-intensive as the Chromium tab being controlled under the hood.

Being said that, you can do it. The trick is finding the perfect balance of the number of tabs and network requests one single Chromium instance can handle on the deployed machine.

In puppeteer sharp that's being solved using extension methods.

await page.QuerySelectorAsync("#my-form")
    .EvaluateFunctionAsync("form => form.submit()"); 

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.