LostBeard/SpawnDev.BlazorJS.WebWorkersv1.2.3

.NET 8.0.NET 9.0.NET 10.0

Call Services and static methods in separate threads with WebWorkers and SharedWebWorkers. Run Blazor WASM in the ServiceWorker.

License

Deps

3

Install Size

—

Vulns

✓ 0

Published

Feb 12, 2026

Get Started

$ dotnet add package SpawnDev.BlazorJS.WebWorkers

Readme

SpawnDev.BlazorJS

Supports .Net 7

An easy Javascript interop library desgined specifcally for client side Blazor.

Use Javascript libraries in Blazor without writing any Javascript code.
Alternative access to IJSRuntime JS is globally available without injection and is usable on the first line of Program.cs
Get and set global proeprties via JS.Set and JS.Get
Create new Javascript objects with JS.New
Get and set object properties via IJSInProcessObjectReference extended methods
Create Callbacks that can be sent to Javascript event listeners or assigned to javascript variables
Easily call Services in separate threads with WebWorkers and SharedWebWorkers

NOTE: The below code shows quick examples. Some objects implement IDisposable, such as all JSObject, IJSInProcessObjectReference, and Callback, and need to be disposed when no longer used.

JS

// Get Set
var innerHeight = JS.Get<int>("window.innerHeight");
JS.Set("document.title", "Hello World!");

// Call
var item = JS.Call<string?>("localStorage.getItem", "itemName");
JS.CallVoid("addEventListener", "resize", Callback.Create(() => Console.WriteLine("WindowResized"), _callBacks));

IJSInProcessObjectReference extended

// Get Set
var window = JS.Get<IJSInProcessObjectReference>("window");
window.Set("myVar", 5);
var myVar = window.Get<int>("myVar");

// Call
window.CallVoid("addEventListener", "resize", Callback.Create(() => Console.WriteLine("WindowResized")));

Create a new Javascript object

var worker = JS.New("Worker", myWorkerScript);

Pass callbacks to Javascript

JS.Set("testCallback", Callback.Create<string>((strArg) => {
    Console.WriteLine($"Javascript sent: {strArg}");
    // this prints "Hello callback!"
}));

// in Javascript
testCallback('Hello callback!');

var audio = JS.New("Audio", "https://some_audio_online");
audio.CallVoid("play");

[JsonConverter(typeof(JSObjectConverter<Audio>))]
public class Audio : JSObject
{
    public Audio(IJSInProcessObjectReference _ref) : base(_ref) { }
    public Audio(string url) : base(JS.New("Audio", url)) { }
    public void Play() => JSRef.CallVoid("play");
}

var audio = new Audio("https://some_audio_online");
audio.Play();

// Program.cs
...
using SpawnDev.BlazorJS;
using SpawnDev.BlazorJS.WebWorkers;

var builder = WebAssemblyHostBuilder.CreateDefault(args);
if (JS.IsWindow)
{
    // we can skip adding dom objects in non UI threads
    builder.RootComponents.Add<App>("#app");
    builder.RootComponents.Add<HeadOutlet>("head::after");
}
// add services
builder.Services.AddSingleton((sp) => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
// SpawnDev.BlazorJS.WebWorkers
builder.Services.AddSingleton<WebWorkerService>();
// app specific services...
builder.Services.AddSingleton<MathsService>();
// build 
WebAssemblyHost host = builder.Build();
// init WebWorkerService
var workerService = host.Services.GetRequiredService<WebWorkerService>();
await workerService.InitAsync();
await host.RunAsync();


// Create a WebWorker
var webWorker = await workerService.GetWebWorker();

// Call a registered service on the worker thread with your arguments
// Action types can be passed for progress reporting
var result = await webWorker.InvokeAsync<MathsService, string>("CalculatePiWithActionProgress", piDecimalPlaces, new Action<int>((i) =>
{
    piProgress = i;
    StateHasChanged();
}));

// Create or get SHaredWebWorker with the provided sharedWorkerName
var sharedWebWorker = await workerService.GetSharedWebWorker("workername");

// Just like WebWorker but shared
// Call a registered service on the worker thread with your arguments
var result = await webWorker.InvokeAsync<MathsService, string>("CalculatePiWithActionProgress", piDecimalPlaces, new Action<int>((i) =>
{
    piProgress = i;
    StateHasChanged();
}));

// Optionally listen for event messages
worker.OnMessage += (sender, msg) =>
{
    if (msg.TargetName == "progress")
    {
        PiProgress msgData = msg.GetData<PiProgress>();
        piProgress = msgData.Progress;
        StateHasChanged();
    }
};

// From SharedWebWorker or WebWorker threads send an event to conencted parents
workerService.SendEventToParents("progress", new PiProgress { Progress = piProgress });

// Or on send an event to a connected worker
webWorker.SendEvent("progress", new PiProgress { Progress = piProgress });