lukehaas/RunJS

Health v2 · maintenance only

Flags: no_license

Adoption not part of the score

2167 stars · 53 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

RunJS is a desktop JavaScript and TypeScript playground for macOS, Windows, and Linux that runs code as you type with instant results. It provides built-in Node.js and browser environments, npm package installation, snippet libraries, and AI-assisted code generation without any project setup.

Use cases

• experiment with an npm package without setting up a project
• learn new JavaScript or TypeScript syntax with instant feedback
• prototype a function in isolation before adding it to a codebase
• quickly transform JSON, CSV, or log data
• test API endpoints with fetch and inspect responses
• sketch React components, SVGs, or canvas animations
• run one-off scripts and calculations
• teach or learn JavaScript with a fast feedback loop

When to choose

• you want a no-setup scratchpad for JS/TS experiments on your desktop
• you need both Node.js and browser APIs in one tool
• you're learning or teaching JavaScript and want instant evaluation
• you want to quickly test regexes, APIs, or libraries

When to avoid

• you need a full IDE or project-based development workflow
• you need a free open-source tool (RunJS uses a paid license)
• you work primarily in languages other than JavaScript/TypeScript
• you need collaborative or browser-based sharing of snippets

Facets

application · maturity active

editor developer-tools cli developer-tools web-development programming-languages education windows javascript-playground typescript scratchpad code-experimentation npm-packages snippet-library prototyping learning-tool macos linux desktop electron nodejs

Member repositories

For agents

markdown · JSON · MCP: product_card(name="lukehaas/RunJS")