microsoft / microsoft/node-api-dotnet

How to accomplish two way communication between .NET and JS?

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Dominant language
C#
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Description

I'm struggling to implement two way communication with this library. Issue might be related to #330.

I'm using .NET as my main program from which I load my JS (ES module, not CommonJS) like this:

[JSExport]
public class TestClass
{
    private NodejsEnvironment NodeJSEnvironment;
    private NodejsPlatform nodejsPlatform;

    public async Task Start()
    {
        var baseDir = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)!;
        var libnodePath = "/path/to/libnode.dll";
        nodejsPlatform = new(libnodePath);
        NodeJSEnvironment = nodejsPlatform.CreateEnvironment("/path/to/project");
        var pid = Process.GetCurrentProcess().Id;
        var inspectionUri = NodeJSEnvironment.StartInspector();
        await NodeJSEnvironment.SynchronizationContext.RunAsync(async () =>
        {
            try
            {
                var jsModule = await NodeJSEnvironment.ImportAsync("./dist/TSTest.js", esModule: true);
                var x = (int)jsModule.CallMethod("callFromDotNet");
            }
            catch (Exception e)
            {
                throw;
            }
        });
    }

    [JSExport]
    public static void CallFromJS()
    {
        Console.WriteLine("Call From JS Success");
    }
}

And my JS file looks like this:

import dotnet from 'node-api-dotnet';

const testClass = dotnet.require('TestClass');
testClass.StaticClass.CallFromJS();

function callFromDotNet() {
    return 42;
}
export { callFromDotNet };

I am using version 0.8.8 for micorosft.javascript.nodeapi and nodeapi.generator nugets. I'm using the same version for JS import.

Issue is that when importing package to JS file I get a crashing error:

Unhandled Exception: System.EntryPointNotFoundException: Arg_EntryPointNotFoundExceptionParameterizedNoLibrary, napi_create_string_utf16
   at System.Runtime.InteropServices.NativeLibrary.GetSymbol(IntPtr, String, Boolean) + 0x57
   at Microsoft.JavaScript.NodeApi.Runtime.NodejsRuntime.CreateString(JSRuntime.napi_env, ReadOnlySpan`1, JSRuntime.napi_value&) + 0x62
   at Microsoft.JavaScript.NodeApi.JSValue.CreateStringUtf16(String) + 0x72
   at Microsoft.JavaScript.NodeApi.JSValue.op_Implicit(String) + 0x15
   at Microsoft.JavaScript.NodeApi.DotNetHost.NativeHost.InitializeModule(JSRuntime.napi_env, JSRuntime.napi_value) + 0x435

I realize that in documentation it says to use import statement like import dotnet from 'node-api-dotnet/net8.0.js'; with ES module but this is also not working for me. I get error: JSException: Package subpath './net8.0.js' is not defined by "exports"

Is documentation found at https://microsoft.github.io/node-api-dotnet/ outdated?

With this code if I remove dotnet import statement and just keep the exported callFromDotNet function from .js file I am able to call JS functions from .NET (one way communication), but how can I also call .NET methods from this same .js file?

Is two way communication like this possible? What am I doing wrong?

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the documentation at https://microsoft.github.io/node-api-dotnet/, issue #330, and the v0.8.8 package exports for node-api-dotnet. Reproduce the napi_create_string_utf16 and package-subpath errors using the C# and ES module examples; done means determining whether the documented import and two-way communication flow work for v0.8.8, with corrected guidance or a confirmed library issue.

Written by the indexing model from the issue text.

Assessment

Tech stack
csharp, javascript
Domain
backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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