@posit-dev/shinyreact

@posit-dev/shinyreact

React hooks and components for Shiny. The Shiny server — Python or R — contains only reactive computation, and the UI is a React client you own. This package is the bridge, and it ships zero UI components: no buttons, no layout, no theme. You bring the component library.

One React client works against an app.py or an app.R server unchanged. The full site covers all three packages.

Do you need this package?

Only if you use a bundler. shinyreact apps come in two tiers:

• No build step — the server serves the same runtime as an IIFE and the client reads it off window.shinyreact. Nothing to install; you can stop reading.
• Bundler (Vite, esbuild, webpack) — npm install this package and import the hooks. You get types, tree-shaking, a development React with Fast Refresh, and your own dependency graph.

Both tiers are built from the same source and speak the same protocol version.

Installation

npm install @posit-dev/shinyreact react react-dom

React 19 is a peer dependency, resolved by your bundler.

Then tell the page entry point that the client brings its own copy, so the server does not also serve the IIFE:

set_react_page(shinyreact_js="client")   # or page_react(), page_react_html(), ReactApp()

page_react(shinyreact_js = "client")

Skip that and the app still works — the registries are page-scoped, so both copies share one set of inputs, outputs, and message handlers — but the page downloads and parses a second React for nothing. The bundle logs a console.warn when it detects this.

Usage

import { useShinyInput, useShinyOutputValue } from "@posit-dev/shinyreact";
import "@posit-dev/shinyreact/styles";
import { createRoot } from "react-dom/client";

function App() {
  const [name, setName] = useShinyInput("name", "world");
  const greeting = useShinyOutputValue("greeting");

  return (
    <div>
      <input value={name} onChange={(e) => setName(e.target.value)} />
      <p>{greeting}</p>
    </div>
  );
}

// The page entry points emit no mount container, so make one.
createRoot(document.body.appendChild(document.createElement("div"))).render(
  <App />,
);

useShinyInput writes to input.name() / input$name on the server; useShinyOutputValue reads whatever the matching reactive_output returned:

@reactive_output
def greeting():
    return f"Hello, {input.name()}!"

output$greeting <- reactive_output({
  paste0("Hello, ", input$name, "!")
})

The "./styles" export is only needed for components that ship CSS (ImageOutput's placeholder spinner); the hooks have no styles of their own.

API

Inputs	useShinyInput · useShinyInputValue · useSetShinyInput
Outputs	useShinyOutputValue · useShinyOutputStatus · useShinyOutputError
Messaging	useShinyMessageHandler
Session	useShinyInitialized · useShinyBusy
Components	ShinyOutput · ImageOutput · ShinyModuleProvider
Utilities	MISSING · PROTOCOL_VERSION

Pick the narrowest hook that fits the call site: a button that pushes events but never reads its own state wants useSetShinyInput, not useShinyInput with a discarded value.

ShinyOutput renders a traditional Shiny output element — a shiny-data-frame, a plotly widget — inside a React tree, and handles binding for you.

Full signatures and types: JS API reference.

Try it

git clone https://github.com/posit-dev/shinyreact
cd shinyreact/examples/11-npm-local
shiny run app.py                 # builds the client bundle on first run

Learn more

• Get started walks through the ui.tsx pattern: inputs, outputs, messages, and embedding traditional Shiny renderers.
• TSX files and JavaScript build tools explains .tsx, JSX, TypeScript, and what npm run build does.
• Client hooks documents every hook in detail.
• The examples catalog lists runnable apps from no-build to Vite + HMR.

License

MIT © Posit Software, PBC