Asynkron.JsEngine

A lightweight JavaScript interpreter written in C# that parses and evaluates JavaScript code using an S-expression intermediate representation.

📚 Documentation

All documentation is organized in the docs/ folder. This is the main entry point for all documentation.

Getting Started

• Quick Start Guide - Installation, basic usage, and first steps
• API Reference - Complete API documentation

Feature Documentation

• Supported Features - Comprehensive list of all implemented JavaScript features with examples
• NPM Package Compatibility - Running npm packages with the engine

Architecture & Design

• Architecture Overview - System design, components, and design decisions
• Transformation Pipeline - How JavaScript code transforms through the pipeline (JS → S-Expr → CPS)
• Documentation Index - Complete documentation index with all implementation details

Implementation Details

• CPS Transformation Plan - Async/await implementation strategy
• ASI Implementation - Automatic Semicolon Insertion
• Signal Pattern - Control flow signal pattern
• Control Flow Alternatives - Alternative approaches for control flow

Investigations & Debugging

• Investigations - Investigation notes and debugging documentation
• Key investigations: Parser vs CPS analysis, promise rejection investigation, exception channel results

Status & Planning

• Feature Status - Current implementation status
• Completed Features - Catalog of implemented features
• Remaining Tasks - What's left to implement

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Quick Overview

Asynkron.JsEngine targets ECMAScript 262 with full language coverage and a steadily growing built-in library.

Current Status

• ECMAScript 262 language: 100% compliant; all language-focused Test262 cases pass.
• Built-ins / standard library: ~50% compliant; about half of the ES built-ins are implemented on the attribute-driven generator model and the rest are being migrated. See docs/FEATURE_STATUS_SUMMARY.md for the latest coverage.

Capabilities

• Variables, functions, classes, objects, arrays
• Async/await, Promises, generators
• ES modules (import/export) including dynamic imports
• Template literals, destructuring, spread/rest, operators, and control flow
• Implemented built-ins include Object, Array/TypedArray/ArrayBuffer/SharedArrayBuffer/DataView, Promise, Math, Date, JSON, RegExp, Reflect, Console, Symbol, Map/Set/WeakMap/WeakSet, BigInt, and async iteration helpers. Standard library coverage is expanding as more types move onto the generated constructor/prototype surface.

See Complete Feature List for detailed documentation with examples.

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Running the Demo

Console application demos are included in the examples folder:

Main Demo

cd examples/Demo
dotnet run

The main demo showcases basic features including variables, functions, closures, objects, arrays, control flow, operators, and standard library usage.

Promise and Timer Demo

cd examples/PromiseDemo
dotnet run

Demonstrates setTimeout, setInterval, Promise creation, chaining, error handling, and event queue processing.

NPM Package Compatibility Demo

cd examples/NpmPackageDemo
dotnet run

Shows that the engine can run pure JavaScript npm packages without Node.js dependencies.

S-Expression Demo

cd examples/SExpressionDemo
dotnet run

Displays the S-expression representation and CPS transformation of JavaScript code. See Transformation Pipeline for details.

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Building and Testing

# Build the solution
dotnet build

# Run tests
cd tests/Asynkron.JsEngine.Tests
dotnet test

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Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

See LICENSE file for details.

Credits

Developed by Asynkron