JSPP (JavaScript++)

JSPP is a modern, experimental transpiler that converts JavaScript and TypeScript code into high-performance, standard C++23.

The primary goal of this project is to achieve a near-perfect translation of JavaScript's dynamic nature and core features into the statically-typed, compiled world of C++, exploring modern C++ capabilities to bridge the gap between these two powerful languages.

About The Project

JavaScript is flexible and dynamic; C++ is performant and type-safe. JSPP aims to offer the best of both worlds. By transpiling JS/TS to C++, we can potentially run JavaScript logic in environments where C++ is native, with significant performance gains and opportunities for low-level interoperability.

This project serves as a deep dive into compiler design, language semantics, and the expressive power of modern C++. The architecture is designed for performance, utilizing:

• Fast Runtime Library: Core JavaScript logic is implemented in a static C++ library (libjspp.a), precompiled for speed.
• Precompiled Headers (PCH): Common headers are precompiled to drastically reduce the front-end parsing time of the C++ compiler.
• NaN-Boxing: An efficient 64-bit value representation (NaN-boxing) is used to replicate JavaScript's dynamic typing with minimal overhead.
• Modern C++23: Leverages the latest language features, including coroutines for async/await and generators.

Features

JSPP currently supports a comprehensive set of JavaScript features:

• Languages: JavaScript (.js) and TypeScript (.ts) support.
• Dynamic Variables: Declaration (let, const, var), assignment, and type changes at runtime.
• Primitive Types: undefined, null, boolean, number, string, symbol.
• Functions:
  • Function declarations, arrow functions, and function expressions.
  • Generators: function* and yield support.
  • Async/Await: async function and await support (built on C++20 coroutines).
  • Closures with proper lexical scoping.
• Object Oriented:
  • Classes: Class declarations, constructors, methods, getters/setters, and inheritance (extends).
  • Prototypes: Prototype chain traversal and manipulation.
• Control Flow:
  • if, else if, else.
  • Loops: for, for-of, for-in, while, do-while.
  • switch statements.
  • try, catch, finally blocks.
• Operators: Full suite of arithmetic, assignment, comparison, logical, bitwise, and unary operators (including typeof, delete, void, instanceof, in).
• Standard Library:
  • Console: log, warn, error, time, timeEnd.
  • Math: Comprehensive Math object implementation.
  • Timers: setTimeout, clearTimeout, setInterval, clearInterval.
  • Promise: Full Promise implementation with chaining.
  • Error: Standard Error class and stack traces.
  • Arrays & Objects: Extensive methods support (map, filter, reduce, push, pop, Object.keys, etc.).

Reserved Keywords

JSPP reserves certain keywords to avoid conflicts with the generated C++ code and internal mechanisms. The following keywords are reserved and cannot be used as variable names:

• jspp: Reserved for internal use by the transpiler.
• std: Reserved to prevent conflicts with the C++ standard library.
• co_yield, co_return, co_await: Reserved for C++ coroutine mechanics.

Using these keywords as variable names will result in a SyntaxError.

Installation

To use JSPP as a command-line tool, install it globally via npm:

npm i @ugo-studio/jspp@latest -g

For Developers

To contribute to JSPP or run its test suite, follow these steps:

Prerequisites

• Bun: This project uses Bun for package management, script execution, and testing.
• C++ Compiler: A compiler with support for C++23 is required (e.g., g++ 13+ or clang 17+).
  • Windows: MSYS2 with mingw-w64-x86_64-gcc is recommended.
  • Linux: g++-14 or equivalent.
  • macOS: brew install gcc.

Setup

1. Clone the repo:

   git clone https://github.com/ugo-studio/jspp.git

2. Install dependencies and build the runtime:

   bun install

   Note: The postinstall script will automatically check for your C++ compiler and setup emsdk for wasm support.

Usage

The primary way to use JSPP is via its command-line interface. This will transpile your file to C++, compile it, and execute the resulting binary.

jspp <path-to-your-file>

Example:

To run a sample TypeScript file located at my-code/test.ts:

jspp my-code/test.ts

The transpiled C++ file and executable will be generated in the same directory as the input file and cleaned up after execution (unless --keep-cpp is used).

Roadmap

This project is ambitious, and there is a long and exciting road ahead. Here is a high-level overview of the planned features and the project's current standing.

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Phase 1: Core Language Features

This phase focuses on building a solid foundation that correctly models JavaScript's core runtime behavior.

• Dynamic Variables & Primitives (NaN-boxing)
• Function Declarations & Arrow Functions
• Correct Hoisting for Variables and Functions
• Closures & Lexical Scoping
• Basic Control Flow (if, loops)
• Basic console API

---

Phase 2: Expanded Language Support

This phase broadens the range of supported JavaScript syntax and features.

• Error Handling: try/catch/finally blocks and throw.
• Objects & Classes: Classes, inheritance, literals, property access.
• Arrays: Literals, indexing, and core methods.
• Operators: Full suite of arithmetic, logical, and comparison operators.
• Advanced Control Flow: switch, for-of, for-in, generators.
• TypeScript Support: Compilation of .ts files.

Phase 3: Interoperability & Standard Library

This phase focuses on building out the standard library and enabling modular code.

• JS Standard Library: Core implementation of Math, Symbol, Error, String, Array, Object, Timer.
• Expanded Library: Date, Temporal, Map, Set, JSON, RegExp.
• Asynchronous Operations: Event loop, Promise, async/await.
• Module System: Support for import and export to transpile multi-file projects.

Phase 4: Optimization & Advanced Features

With a feature-complete transpiler, the focus will shift to performance and advanced capabilities.

• Architecture Optimization: Static library runtime and Precompiled Headers.
• Performance Benchmarking: Create a suite to compare transpiled C++ performance against V8.
• Linker Optimization: Support for LLD or Mold linkers.
• C++ Interoperability: Define a clear API for calling C++ functions from JavaScript.

Contributing

Contributions are what make the open-source community such an amazing place to learn, inspire, and create. Any contributions you make are greatly appreciated.

1. Fork the Project
2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
3. Commit your Changes (git commit -m 'Add some AmazingFeature')
4. Push to the Branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

License

Distributed under the MIT License. See LICENSE for more information.