pkg-r

shinyreact (R)

React UI infrastructure for Shiny. The Shiny server contains only reactive computation; the UI is a React client you own. shinyreact provides the bridge — it ships zero UI components itself. The same JavaScript bundle backs both the R and Python packages.

Overview

shinyreact implements the ui.tsx pattern: write the UI in a client React codebase and bootstrap it from R with page_react_html(). The server publishes data with reactive_output(), pushes messages with send_message(), and reads inputs sent by the client's useShinyInput hooks.

Installation

shinyreact is pre-release and not yet on CRAN. Install the development version from GitHub (the package lives in the pkg-r/ subdirectory of the monorepo):

# install.packages("pak")
pak::pak("posit-dev/shinyreact/pkg-r")

Usage

A minimal app.R. The UI lives in www/ (ui.js, plus ui.css if you want styles — discovered automatically); the server owns only reactive computation:

library(shiny)
library(shinyreact)

ui <- page_react() # discovers www/ui.js + www/ui.css

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

shinyApp(ui, server)

reactive_output() sends any JSON-serializable value through unchanged; the client reads it with useShinyOutputValue("greeting"). Push data to the client with send_message().

Traditional Shiny renderers (e.g. plotly::renderPlotly()) work too, rendered client-side with the ShinyOutput React component — their binding JS/CSS is discovered from the render function and delivered to the client automatically, no *Output() placeholder needed.

See examples/01-hello/ for the complete runnable app (app.R alongside the equivalent app.py, sharing one www/ client).

Get started

• Function reference: https://posit-dev.github.io/shinyreact/r
• Examples: the examples catalog

Agent Skills

The package ships two Agent Skills, so a coding agent can build a shinyreact app without you pasting this README into it:

• shinyreact-build-app — build a ui.tsx-pattern app from scratch
• shinyreact-convert-app — port an existing Shiny app to the pattern

Agents using btw discover them automatically once shinyreact is attached. To copy them into a project for Claude Code and other skill-aware tools:

btw::btw_skill_install_package("shinyreact")