Default Services

Among others:

Service	Lifetime	Description
`IJSRuntime`	Scoped	An instance of a JavaScript runtime where JS calls are dispatched
`NavigationManager`	Scoped	Helpers for working with URI and navigation state

Adding & Using Services

Note: In ASP.NET Core apps, scoped services are typically scoped to the current request. In Blazor Server apps, the request scope lasts for the duration of the client connection.

Program.cs

var builder = WebApplication.CreateBuilder(args);

// builder has an IServiceCollection which is a list of service descriptor objects
builder.Services.AddRazorPages();
builder.Services.AddServerSideBlazor();
builder.Services.AddSingleton<WeatherForecastService>();
builder.Services.AddSingleton<ISomeService, SomeService>();

Detect Transient Disposables in Blazor Server Apps

How a Component Can Access Services from a Different DI Scope

If a component invokes an async method that executes code in a different DI scope, they do not have access to the DI container’s services (like IJSRuntime). An example is HttpClient instances instantiated from IHttpClientFactory, which have their own DI scope.

To resolve, create a class BlazorServiceAccessor that defines an AsyncLocal which stores the IServiceProvider for the current async context. An instance of this class can be acquired from within a different DI scope.

internal sealed class BlazorServiceAccessor
{
    private static readonly AsyncLocal<BlazorServiceHolder> s_currentServiceHolder = new();

    public IServiceProvider? Services
    {
        get => s_currentServiceHolder.Value?.Services;
        set
        {
            if (s_currentServiceHolder.Value is { } holder)
                holder.Services = null; // Clear the current IServiceProvider trapped in the AsyncLocal.

            if (value is not null)
                // Use object indirection to hold the IServiceProvider in an AsyncLocal
                // so it can be cleared in all ExecutionContexts when it's cleared.
                s_currentServiceHolder.Value = new() { Services = value };
        }
    }

    private sealed class BlazorServiceHolder
    {
        public IServiceProvider? Services { get; set; }
    }
}