just.js

small, embeddable V8 JavaScript runtime for Linux

TLDR

Start a REPL (interactive shell)

$ just

Run a JavaScript file

$ just [path/to/file.js]

Run a script piped from stdin

$ cat [path/to/file.js] | just --

Evaluate JavaScript code

$ just eval "[just.print(just.memoryUsage().rss)]"

Initialize a new project

$ just init [project_name]

Build a JavaScript application into a static executable

$ just build [path/to/file.js] --clean --static

Clean a built project

$ just clean

SYNOPSIS

just [file | -- | command] [options]

just is a small, embeddable V8 JavaScript runtime for Linux. It is a thin layer over system calls, V8 and the C/C++ standard library, giving scripts direct access to Linux primitives such as epoll.The runtime is designed to be lightweight and fast-starting, suitable for system software, network servers and command-line tools. Modules use CommonJS, calls are blocking by default, and the event loop is implemented in JavaScript. Applications can be compiled into standalone executables.

PARAMETERS

eval CODE

Evaluate a JavaScript code string.

init NAME

Initialize a new project directory.

build [FILE]

Build JavaScript into a native executable.

clean

Remove build artifacts of a project.

Read the script from standard input.

--static

Create a statically linked executable (build).

--clean

Clean before building (build).

CAVEATS

Linux x86_64 only. The API differs completely from Node.js; npm packages generally do not work. No ES module support. The project is not actively maintained since November 2023; its author has moved to a successor runtime called lo.

HISTORY

just-js was created by Andrew Johnston (billywhizz) around 2020 as a minimal V8 runtime for Linux. It gained attention for reaching the top of the TechEmpower web framework benchmarks. The last release, 0.1.13, was published in October 2022.

RESOURCES

Source code · Homepage