RexxJS

A modern REXX for JavaScript runtimes. Run classic REXX with powerful new libraries in Node.js, browsers, and standalone binaries — with first-class cross-application messaging.

Getting Started

• Try in browser: Online REPL
• Explore the language: Reference
• Get the code: GitHub (coming soon)

Quick Example

-- Modern variable assignment
LET data = [1, 2, 3, 4, 5]
LET processed = MAP(data, "x * 2")
SAY processed

-- Pipe operator with named parameters
LET result = "  hello world  "
  |> STRIP()
  |> SUBSTR(start=7, length=5)
-- Result: "world"

-- Load libraries with operations and functions
REQUIRE "cwd:libs/bathhouse.js"
SERVE_GUEST guest="river_spirit"        -- Operation: side effect
LET count = COUNT_TOKENS()               -- Function: returns value

Why RexxJS

Core Strengths

• Familiar REXX syntax with modern ergonomics (variables, loops, subroutines)
• Multi-environment execution: Run the same script in Node.js, browsers, or standalone binaries
• Pipe operator (|>) with named parameters for elegant data transformations
• Operations vs Functions architecture: imperative commands and pure functions working together
• 500+ functions across filesystems, strings, math, time, web, DOM, and more

Integration and Automation

• Cross-application control via ADDRESS statement for orchestrating systems
• Control-bus scripting with sandboxed iframe execution and real-time progress monitoring
• Web automation with gray-box testing via DOM queries, element filtering, and chainable operations
• Remote execution for containers and VMs (Docker, Podman, QEMU, VirtualBox, Proxmox)
• Gray-box browser testing - combine white-box (DOM access) with black-box (user interactions)

Data and Functions

• Function pipelines - FILTER_BY_ATTR, GET_VALUES, GET_TEXT chain DOM data extraction
• Flexible parameters: Both positional and named styles work everywhere
• Dynamic function discovery - INFO() and FUNCTIONS() for runtime introspection
• Data tooling: R- and SciPy-inspired helpers for analysis and transformation
• SQLite integration for lightweight persistence
• HTTP API integration with automatic retry and error handling

Distribution

• Standalone binary ./rexx — no Node.js required
• Node.js CLI node core/src/cli.js — great for dev
• Test runner ./rexxt — TUI experience

Use Cases

Web and Browsers

• Browser automation with gray-box testing (DOM + user interactions)
• Cross-iframe scripting via control-bus architecture
• Real-time progress monitoring in web applications
• Web scraping and data extraction with pipeline operators

Node.js and CLI

• System administration and infrastructure automation
• Container and VM orchestration (Docker, Podman, QEMU, etc.)
• Local and remote script execution
• File system operations and command orchestration

Data and Integration

• Data analysis and transformation with piped operations
• API integration and HTTP workflows
• Database tasks with SQLite
• Statistical computing with R/SciPy-inspired functions

Testing and Automation

• System integration testing with gray-box capabilities
• Multi-application orchestration via ADDRESS handlers
• Resilient workflows with retry logic and error handling
• Infrastructure-as-code for VMs and containers

Looking for specifics? Jump to the Reference.

RexxJS brings the power of REXX to modern JavaScript environments.