Just – very small v8 JavaScript runtime

Just is a very small v8 JavaScript runtime for Linux only.

Just is no longer actively maintained. The developer is working on Io, a low-level JavaScript runtime.

This is free and open source software.

Goals of the project were:

  • Small, secure, robust and performant js runtime.
  • Small codebase. easy to understand and hack.
  • Very simple layer on top of system calls, v8 and c/c++ standard libraries.
  • Minimal use of classes/function templates and OO – “c” in JavaScript.
  • Favour return codes over exceptions.
  • Platform for building system software on linux in JavaScript.
  • As close to native performance as possible.
  • Aecure by default.
  • Avoid abstraction as much as possible. abstractions can be built in userland.
  • commonjs modules, no support for ES modules.
  • non-async by default – can do blocking calls and not use the event loop.
  • Event loop in JS-land. full control over epoll api.
  • Small standard library – leave as much to userland as possible. focus on primitives needed to build higher level abstractions.
  • Useful as a teaching/learning platform for linux system programming and learning more about JavaScript and v8 internals.
  • Small number of source files.
  • Minimal dependencies – g++ and make only.
  • Keep LOC as small as possible < 5k.
  • Allocate as little as possible on v8 heap.

Support: GitHub Code Repository
Developer: Andrew Johnston
License: MIT License

Just is written in JavaScript and C++. Learn JavaScript with our recommended free books and free tutorials. Learn C++ with our recommended free books and free tutorials.

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