RunJS v4.0.4 — JavaScript & TypeScript playground for desktop
RunJS is a desktop scratchpad where JavaScript runs as you type—ideal for proving an idea, testing a regex, prototyping a snippet, or experimenting with npm packages without spinning up a whole project.
It combines Node.js and browser-style capabilities in one workspace, which goes beyond a plain terminal REPL or a narrow browser console session.
What RunJS is good for
Instant feedback: evaluate code continuously while editing to see outputs and behavior immediately.
Deep inspection: inspect values with workflows like Magic Comments and Logpoints so you can observe results without littering console.log everywhere.
NPM experiments: install and try libraries quickly when you want to learn an API or compare approaches.
Snippet workflow: build a personal snippet library for recurring patterns and teaching demos.
Modern tooling: TypeScript-oriented workflows are supported via the product’s TypeScript playground direction (see official docs/pages for current capabilities).
AI-assisted exploration: the product highlights generating and running code with AI assistance for faster iteration.
Who uses it
Front-end engineers, instructors, and learners who want a clean, focused environment for small experiments—especially during screen shares, interviews, or daily “what does this do?” checks.
Version
- Version: 4.0.4
- Official site: runjs.app
RunJS is positioned as a cross-platform desktop app; verify macOS requirements on the download page for your build.
