runcode: Construct to let you run arbitrary R code live in a Shiny app

In daattali/shinyjs: Easily Improve the User Experience of Your Shiny Apps in Seconds

Construct to let you run arbitrary R code live in a Shiny app

Description

Sometimes when developing a Shiny app, it's useful to be able to run some R code on-demand. This construct provides your app with a text input where you can enter any R code and run it immediately.

This can be useful for testing and while developing an app locally, but it should not be included in an app that is accessible to other people, as letting others run arbitrary R code can open you up to security attacks.

To use this construct, you must add a call to runcode() in the UI of your app, and initialize shinyjs with a call to useShinyjs().

Usage

runcode(
  code = "",
  type = c("text", "textarea", "ace"),
  width = NULL,
  height = NULL,
  ns = shiny::NS(NULL)
)

Arguments

code	The initial R code to show in the text input when the app loads
type	One of "text" (default), "textarea", or "ace". When using a text input, the R code will be limited to be typed within a single line, and is the recommended option. Textarea should be used if you want to write long multi-line R code. Note that you can run multiple expressions even in a single line by appending each R expression with a semicolon. Use of the "ace" editor requires the shinyAce package.
width	The width of the editable code input (ignored when type="ace")
height	The height of the editable code input (ignored when type="text")
ns	The namespace object of the current module if inside a Shiny module.

Note

You can only have one runcode construct in your shiny app, do not call it more than once in the UI.

See Also

useShinyjs

Examples

if (interactive()) {
  library(shiny)

  shinyApp(
    ui = fluidPage(
      useShinyjs(),  # Set up shinyjs
      runcode(code = "shinyjs::alert('Hello!')")
    ),
    server = function(input, output) {}
  )
}

daattali/shinyjs documentation built on June 11, 2025, 6:07 p.m.