DotNetJS 0.3.8

DotNetJS

This project is dedicated to providing user-friendly workflow for consuming .NET C# programs and libraries in any JavaScript environment, be it web browsers, Node.js or custom restricted spaces, like web extensions for VS Code.

The solution is based on two main components:

• JavaScript/dotnet-runtime (npm). Consumes compiled C# assemblies and .NET runtime WebAssembly module to provide C# interoperability layer in JavaScript. The library is environment-agnostic — it doesn't depend on platform-specific APIs, like browser DOM or node modules and can be imported as CommonJS or ECMAScript module or consumed via script tag in browsers.
• DotNet/DotNetJS (NuGet). Provides JavaScript interoperability layer in C# and packs project output into single-file JavaScript library via MSBuild task. Produced library contains dotnet-runtime initialized with the project assemblies and ready to be used as interoperability layer for the packaged C# project. Can optionally emit type definitions to bootstrap TypeScript development.

Quick Start

In C# project configuration file specify Microsoft.NET.Sdk.BlazorWebAssembly SDK and import DotNetJS NuGet package:

<Project Sdk="Microsoft.NET.Sdk.BlazorWebAssembly">

    <PropertyGroup>
        <TargetFramework>net6.0</TargetFramework>
    </PropertyGroup>

    <ItemGroup>
        <PackageReference Include="DotNetJS" Version="*"/>
    </ItemGroup>

</Project>

To associate a JavaScript function with a C# method use JSFunction attribute. To expose a C# method to JavaScript, use JSInvokable attribute:

using System;
using DotNetJS;
using Microsoft.JSInterop;

namespace HelloWorld;

partial class Program
{
    // Entry point is invoked by the JavaScript runtime on boot.
    public static void Main ()
    {
        // Invoking 'dotnet.HelloWorld.GetHostName()' JavaScript function.
        var hostName = GetHostName();
        // Writing to JavaScript host console.
        Console.WriteLine($"Hello {hostName}, DotNet here!");
    }
    
    [JSFunction] // The interoperability code is auto-generated.
    public static partial string GetHostName ();

    [JSInvokable] // The method is invoked from JavaScript.
    public static string GetName () => "DotNet";
}

Publish the project with dotnet publish. A single-file dotnet.js library will be produced under the "bin" directory. Consume the library depending on the environment:

Browser

<script src="dotnet.js"></script>

<script>

    // Providing implementation for 'GetHostName' function declared in 'HelloWorld' C# assembly.
    dotnet.HelloWorld.GetHostName = () => "Browser";
    
    window.onload = async function () {
        // Booting the DotNet runtime and invoking entry point.
        await dotnet.boot();
        // Invoking 'GetName()' C# method defined in 'HelloWorld' assembly.
        const guestName = dotnet.HelloWorld.GetName();
        console.log(`Welcome, ${guestName}! Enjoy your global space.`);
    };
    
</script>

Node.js

// Import as CommonJS module.
const dotnet = require("dotnet");
// ... or as ECMAScript module in node v17 or later.
import dotnet from "dotnet.js";

// Providing implementation for 'GetHostName' function declared in 'HelloWorld' C# assembly.
dotnet.HelloWorld.GetHostName = () => "Node.js";

(async function () {
    // Booting the DotNet runtime and invoking entry point.
    await dotnet.boot();
    // Invoking 'GetName()' C# method defined in 'HelloWorld' assembly.
    const guestName = dotnet.HelloWorld.GetName();
    console.log(`Welcome, ${guestName}! Enjoy your module space.`);
})();

Example Projects

Find the following sample projects in this repository:

• Hello World — Consume the produced library as a global import in browser, CommonJS or ES module in node.
• Web Extension — Consume the library in VS Code web extension, which works in both web and standalone versions of the IDE.
• Runtime Tests — Integration tests featuring various usage scenarios: async method invocations, interop with instances, sending raw byte arrays, streaming, etc.

Build Properties

Specify following optional properties in .csproj to customize the build:

• <EmitSourceMap>true</EmitSourceMap> — emit JavaScript source map file.
• <EmitTypes>true</EmitTypes> — emit TypeScript type definitions file.

For example, following configuration will emit source map and type definitions:

<Project Sdk="Microsoft.NET.Sdk.BlazorWebAssembly">

    <PropertyGroup>
        <TargetFramework>net6.0</TargetFramework>
        <EmitSourceMap>true</EmitSourceMap>
        <EmitTypes>true</EmitTypes>
    </PropertyGroup>

    <ItemGroup>
        <PackageReference Include="DotNetJS" Version="*"/>
    </ItemGroup>

</Project>

Compiling Runtime

To compile and test the runtime run the following in order (under dotnet-runtime folder):

scripts/install-emsdk.sh
scripts/compile-runtime.sh
npm build
scripts/compile-test.sh
npm test

Publishing Runtime

A memo for the publishing process after modifying dotnet-runtime:

1. Bump NPM version on JavaScript/dotnet-runtime/package.json and:

• npm run build
• scripts/publish-package.sh

2. Bump NuGet version on DotNet/DotNetJS/DotNetJS.csproj and:

• dotnet pack -c Release --output bin
• dotnet nuget push bin/DotNetJS.{VER}.nupkg --api-key {KEY} --source https://api.nuget.org/v3/index.json