How to call C# methods from JavaScript?

Sorry if this is considered a duplicate of this thread, I didn't want to hijack/ necro that thread.

I'm trying to invoke C# methods from JavaScript, and having trouble accomplishing this.

Are we meant to use `ccall` and `cwrap`, as outlined here? When I tried to add `EXTRA_EXPORTED_RUNTIME_METHODS['cwrap']` to the arguments of my Emscripten build settings, the build tools threw an error:
>error: Emscripten LinkerSettings contains setting for which a dedicated parameter exists: EXTRA_EXPORTED_RUNTIME_METHODS (System.InvalidOperationException)

Is there somewhere I am meant to configure this outside the Emscripten settings?

Another method I see is using `dynCall` methods, but documentation on these methods is scarce, and I've had no luck with all previous examples.

I'm at a bit of a loss on how to proceed. Any ideas or documentation?

 

With a bit of digging, I figured out there were multiple dynCall variants; the only variants that worked for me was the dynCall_* variant:

Code (CSharp):

1. dynCall_v(callback); // this works
2. //dynCall('v', callback); // ReferenceError: dynCall is not defined
3. //Module['dynCall_v'](callback); // TypeError: Module.dynCall_v is not a function

I'll be sharing an example Project Tiny repo with bidirectional C# <-> JavaScript shortly.

 

̶I̶ ̶m̶a̶d̶e̶ ̶a̶n̶ ̶e̶x̶a̶m̶p̶l̶e̶ ̶p̶r̶o̶j̶e̶c̶t̶ ̶w̶i̶t̶h̶ ̶i̶n̶t̶e̶r̶o̶p̶e̶r̶a̶b̶i̶l̶i̶t̶y̶ ̶b̶e̶t̶w̶e̶e̶n̶ ̶C̶#̶ ̶a̶n̶d̶ ̶J̶a̶v̶a̶S̶c̶r̶i̶p̶t̶ ̶h̶e̶r̶e̶.̶ ̶T̶h̶e̶ ̶J̶a̶v̶a̶S̶c̶r̶i̶p̶t̶ ̶t̶o̶ ̶C̶#̶ ̶e̶x̶a̶m̶p̶l̶e̶s̶ ̶r̶e̶q̶u̶i̶r̶e̶ ̶y̶o̶u̶ ̶t̶o̶ ̶p̶a̶s̶s̶ ̶t̶h̶e̶ ̶f̶u̶n̶c̶t̶i̶o̶n̶ ̶y̶o̶u̶ ̶w̶a̶n̶t̶ ̶t̶o̶ ̶c̶a̶l̶l̶ ̶a̶s̶ ̶a̶ ̶d̶e̶l̶e̶g̶a̶t̶e̶.̶

If anyone has info on how to call an arbitrary static C# function from JavaScript in Unity, please let me know!

EDIT: Removed project link.

 

Hey Sine, thanks for putting up the example - I'm at a bit of a loss to how to call the callback methods from the javascript console though.

If you could offer any advice that'd be greatly appreciated!

 

Hi @SINePrime. I'm currently building a game with Unity Tiny and I need to call C# function from JS. I'm able to call JS function from C# and to do callbacks like this => C# to JS to C#, but I'm not able to call C# function from JS. I'm not able to get the example project you mentionned earlier in your post.

 

Sorry, I removed the project link because the official Getting Started guide now contains JavaScript interoperability instructions.

As far as calling arbitrary C# from JavaScript, I don't think it's possible. You'll have to do something like pass all the C# delegates you need to JavaScript using an initialization function.

 

I talked to one of the Tiny Dev member and said that I have to basically use the callaback approach. C# needs to give JS a callback method to use, and then JS can call it. However, I don't know how JS can call the callback..

 

C# function from JS sample.

Code (CSharp):

1. using System;
2. using Unity.Entities;
3. using System.Runtime.InteropServices;
4. using AOT;
5.  
6. public class MySystem : SystemBase
7. {
8.     delegate void FizzBuzzDelegate(int num, string fizzBuzz);
9.  
10.     [DllImport("__Internal")]
11.     private static extern void callbackInit(FizzBuzzDelegate callback);
12.  
13.     [MonoPInvokeCallback(typeof(FizzBuzzDelegate))]
14.     private static void FizzBuzzCallback(int num, string fizzBuzz)
15.     {
16.         Console.WriteLine("[C#] " + num + ":" + fizzBuzz);
17.     }
18.  
19.     protected override void OnCreate()
20.     {
21.         callbackInit(FizzBuzzCallback);
22.     }
23.  
24.     protected override void OnUpdate()
25.     {
26.     }
27. }
28.  

Code (JavaScript):

1. mergeInto(LibraryManager.library, {
2.     $num: 0,
3.     $fizzBuzzCallbackPointer: 0,
4.  
5.     $timerFunc: function () {
6.         setInterval(function () {
7.             num++;
8.             var fizzBuzz = '';
9.             if (!(num % 15)) fizzBuzz = 'FizzBuzz';
10.             else if (!(num % 3)) fizzBuzz = 'Fizz';
11.             else if (!(num % 5)) fizzBuzz = 'Buzz';
12.             else if (!fizzBuzz) fizzBuzz = num.toString();
13.             var len = lengthBytesUTF8(fizzBuzz) + 1;
14.             var ptr = _malloc(len);
15.             stringToUTF8(fizzBuzz, ptr, len);
16.             dynCall_vii(fizzBuzzCallbackPointer, num, ptr);
17.             _free(ptr);
18.         }, 1000);
19.     },
20.  
21.     callbackInit__deps: ['$fizzBuzzCallbackPointer', '$num', '$timerFunc'],
22.     callbackInit: function (callbackPtr) {
23.         fizzBuzzCallbackPointer = callbackPtr;
24.         timerFunc();
25.     }
26. });

 

Thanks a lot! I was able to do exactly what I wanted to do! It is really appreciated! Also do you know if there is a way to know if our game is LOADED in the browser and how we can UNLOAD it?

 

Quick question, i'm attempting to work on a solution to this as I think there isnt a way.... but is there away to have external JS (so perhaps in the HTML page itself rather than as part of the 'mergeInto' embedded JS) call CSharp functions?