J (J language) is a high-level, general-purpose, high-performance programming language. J is portable and runs on 32/64-bit Windows/Linux/Mac as well as iOS, Android, and other platforms. J source (required only if Jsoftware binaries don't meet your requirements) is available under both commercial and GPL 3 license. J systems can be installed and distributed for free.

J systems have:

• an integrated development environment
• standard libraries, utilities, and packages
• console, browser, and Qt front ends
• interfaces with other programming languages and applications
• integrated graphics
• memory mapped files for high performance data applications
• Jd 

Flurl is a modern, fluent, asynchronous, testable, portable, buzzword-laden URL builder and HTTP client library. 

<p>Sync rendered by thread @IdOfRenderingThread</p>

@code
{
  int IdOfRenderingThread;

  protected override void OnInitialized()
  {
    base.OnInitialized();
    IdOfRenderingThread =
      System.Threading.Thread.CurrentThread.ManagedThreadId;
  }
}

@page "/"

<h1>Components with synchronous OnInitialized()</h1>
@for (int i = 0; i < 5; i++)
{
  <SynchronousInitComponent />
}

Components with synchronous OnInitialized()
Sync rendered by thread 4
Sync rendered by thread 4
Sync rendered by thread 4
Sync rendered by thread 4
Sync rendered by thread 4

<p>Async rendered by thread @IdOfRenderingThread</p>

@code
{
  int IdOfRenderingThread;

  protected override async Task OnInitializedAsync()
  {
    // Runs synchronously as there is no code in base.OnInitialized(),
    // so the same thread is used
    await base.OnInitializedAsync().ConfigureAwait(false);
    IdOfRenderingThread =
      System.Threading.Thread.CurrentThread.ManagedThreadId;

    // Awaiting will schedule a job for later, and we will be assigned
    // whichever worker thread is next available
    await Task.Delay(1000).ConfigureAwait(false);
    IdOfRenderingThread =
      System.Threading.Thread.CurrentThread.ManagedThreadId;
  }
}

@page "/async-init"

<h1>Components with asynchronous OnInitializedAsync()</h1>
@for (int i = 0; i < 5; i++)
{
  <AsynchronousInitComponent/>
}

Components with asynchronous OnInitializedAsync()
Async rendered by thread 4
Async rendered by thread 4
Async rendered by thread 4
Async rendered by thread 4
Async rendered by thread 4

Components with asynchronous OnInitializedAsync()
Async rendered by thread 7
Async rendered by thread 18
Async rendered by thread 10
Async rendered by thread 13
Async rendered by thread 11

        public async Task<IList<NewsSliderModel>> GetNewsSliderTable(CancellationToken cancellationToken = default(CancellationToken))
        {
            IQueryable<News> selectednews = _news.Take(_sliderTakeCount).AsQueryable();
             ...
             ...
            return await selectednews.Select(x => new NewsSliderModel
            {
                NewsId = x.Id,
                Title = x.Title,
                ImagePath = x.ImagePath,
                ImageTitle = x.ImageTitle,
                ImageDescription = x.ImageDescription,
            }).ToListAsync();

        }

        public virtual async Task<ActionResult> MainSlider()
        {
            IList<NewsSliderModel> SliderList = await _newsService.GetNewsSliderTable(Order.Descending, NewsOrderBy.Id);
            return PartialView(MVC.Home.Views._MainSlider, SliderList.ToList());
        }

HttpServerUtility.Execute blocked while waiting for an asynchronous operation to complete.

if(person == null) { }

if(person is null) { }

public class Person
{
  public static bool operator ==(Person x, Person y)
  {
    return false;
  }
  public static bool operator !=(Person x, Person y)
  {
    return !(x == y);
  }
  public override bool Equals(object obj)
  {
    return base.Equals(obj);
  }
}

Person person = null;
Console.WriteLine("Is Person null?");
Console.WriteLine($"== says: {person == null}");
Console.WriteLine($"is says: {person is null}");

Is Person null?
== says: True
is says: True

Is Person null?
== says: False
is says: True

public static bool operator ==(Person x, Person y)
{
   return false;
}

Don't use window.event

Five Things About RxJS and Reactive Programming 

Safe Systems Programming in C# and .NET