@jupyter-kit/executor-webr

In-browser R executor for @jupyter-kit/core. Wraps WebR (webr on npm) which runs the R interpreter compiled to WebAssembly inside its own dedicated worker.

⚠️ License caveat — this package is GPL

R itself is licensed under GPL-2.0-or-later. The webr npm package bundles R, so it inherits GPL. Because this wrapper imports webr at runtime, it is also distributed under GPL-2.0-or-later.

If you ship an app that uses @jupyter-kit/executor-webr, your distribution as a whole must comply with GPL — typically that means publishing your application's source under a GPL-compatible licence when you distribute the binary/bundle.

The other packages in this monorepo (core, react, theme, syntax, mathjax, mathjax-cdn, katex, katex-cdn, editor-codemirror, executor-pyodide) remain Apache-2.0 — they don't link against R, so they're unaffected.

If you're not OK with GPL, swap this package out for a server-side R executor (HTTP/WebSocket bridge to a hosted Rserve) and keep your client Apache-2.0.

Install

pnpm add @jupyter-kit/executor-webr @jupyter-kit/core

Usage

import { createWebRExecutor } from '@jupyter-kit/executor-webr';
import { r as rHighlight } from '@jupyter-kit/core/langs/r';
import { StreamLanguage } from '@codemirror/language';
import { r as rEditor } from '@codemirror/legacy-modes/mode/r';

const executor = createWebRExecutor({
  packages: ['ggplot2'],   // optional: install on boot
  onStatus: (s) => console.log('webr:', s),
});

createRenderer({
  language: 'r',
  languages: [rHighlight],
  executor,
  plugins: [createEditorPlugin({ languages: { r: StreamLanguage.define(rEditor) } })],
});

What you get

• stdout / stderr captured per cell.
• Last-evaluated value as text/plain (R's print() output).
• Errors with R's conditionMessage as the traceback.
• Persistent R session across cells (variables retained).

Options

| Option | Default | Notes | |---|---|---| | baseURL | https://webr.r-wasm.org/latest/ | WASM / worker assets prefix | | packages | [] | R packages to install on boot | | onStatus | — | 'idle' / 'loading' / 'installing' / 'running' / 'ready' / 'error' |

Bundle size

~1.5KB gz for the wrapper. WebR itself (~30MB including R + base packages) is fetched lazily from baseURL on first execution.

License

GPL-2.0-or-later — see warning above.