Calling a Blazor method From JavaScript

blazor javascript visual-studio


I'm experimenting with Blazor in Visual Studio, specifically with calling Blazor code from JavaScript. I'm reasonably confident that I've got all the right libraries in place. However, when I attempt to call my Blazor method with invokeMethodAsync, I get the message "no .net call dispatcher has been set". In my Index.Html file, I have this:

<script> DotNet.invokeMethodAsync("BlazorFour.App", "HelloYou").then(data => alert(data), reason => alert(reason)); </script>

(It's the alert(reason) that generates the error message)

I've added a class file to my Blazor project and it contains this:

using Microsoft.JSInterop;
using System.Threading.Tasks;
public class HelloWorld
public static Task<string> HelloYou()
    return Task.FromResult("Hello, ");

I've used all the templates in Visual Studio and the dotnet -new blazor commandline utility to create my start points but get the same message in all of the projects. It's seems likely to me that I'm missing something fundamental here.

8/6/2018 3:27:21 PM

Popular Answer

Peter Vogel: It would be great if you could call Blazor C# methods from your JavaScript code. Right now, that's not quite possible: Simply calling Blazor C# from JavaScript won't work (you'll get a message about a call dispatcher not being available).

What you can do, however, is once your Blazor code is running, call JavaScript code from your C# code. Once you've done that, your JavaScript code can, in turn, call Blazor code.

Hope this solves the problem...

8/28/2018 6:59:33 PM

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