Author: Dean Attali
Date: 2016-12-26

# Package shinyjs

#### Dean Attali

#### 2016-12-26

# shinyjs - Easily improve the user interaction and user experience in your Shiny apps in seconds

> Copyright 2016 Dean Attali

`shinyjs` lets you perform common useful JavaScript operations in Shiny apps that will greatly improve your apps without having to know any JavaScript.

Examples include: hiding an element, disabling an input, resetting an input back to its original value, delaying code execution by a few seconds, and many more useful functions for both the end user and the developer. `shinyjs` can also be used to easily call your own custom JavaScript functions from R.

shinyjs was developed for non-commerical purposes. For commerical usage, please contact me. If you find shinyjs useful, please consider supporting its development!

# Table of contents

- Demos and tutorials
- Overview of main functions
- Installation
- How to use
- Basic use case - complete working example
- Calling your own JavaScript functions from R
- FAQ and extra tricks
- Colour Picker input & addin
- More resources

## Demos and tutorials

- Demo Shiny app that lets you play around with some of the functionality in `shinyjs`.
- Video of my shinyjs talk (30 min) and the corresponding presentation slides from the 2016 Shiny Developer Conference.
- Video of my shinyjs talk (5 min) and the corresponding presentation slides from the 2016 useR Conference.

## Overview of main functions

Note: In order to use any `shinyjs` function in a Shiny app, you must first call `useShinyjs()` anywhere in the app’s UI.

Function | Description
--- | ---
`show`/`hide`/`toggle` | Display or hide an element (optionally with an animation).
`hidden` | Initialize a Shiny tag as invisible (can be shown later with a call to `show`).
`enable`/`disable`/`toggleState` | Enable or disable an input element, such as a button or a text input.
`disabled` | Initialize a Shiny input as disabled.
`reset` | Reset a Shiny input widget back to its original value.
`delay` | Execute R code (including any `shinyjs` functions) after a specified amount of time.
`alert` | Show a message to the
`html` | Change the text/HTML of an element.
`onclick` | Run R code when a specific element is clicked. Was originally developed with the sole purpose of running a `shinyjs` function when an element is clicked, though any R code can be used.
`onevent` | Similar to `onclick`, but can be used with many other events instead of click (for example, listen for a key press, mouse hover, etc).
`addClass`/`removeClass`/`toggleClass` | add or remove a CSS class from an element.
`runjs` | Run arbitrary JavaScript code.
`extendShinyjs` | Allows you to write your own JavaScript functions and use `shinyjs` to call them as if they were regular R code. More information is available in the section “Calling your own JavaScript functions from R” below.

### Functions that help you during Shiny app development

Function | Description
--- | ---
`runcodeUI`+`runcodeServer` | Adds a text input to your app that lets you run arbitrary R code live.
`showLog` | Print any JavaScript `console.log()` messages in the R console, to make it easier and quicker to debug apps without having to open the JS console.
`logjs` | Print a message to the JavaScript console (mainly used for debugging purposes).
`inlineCSS` | Easily add inline CSS to a Shiny app.

Check out the shinyjs demo app to see some of these in action, or install `shinyjs` and run `shinyjs::runExample()` to see more demos.

## Installation

To install the stable CRAN version:

    install.packages("shinyjs")

To install the latest development version from GitHub:

    install.packages("devtools")
    devtools::install_github("daattali/shinyjs")

## How to use

A typical Shiny app has a UI portion and a server portion. Before using most shinyjs functions, you need to call `useShinyjs()` in the app’s UI. It’s best to include it near the top as a convention.

Here is a minimal Shiny app that uses `shinyjs`:

    library(shiny)
    library(shinyjs)

    ui <- fluidPage(
      useShinyjs(),  # Include shinyjs

      actionButton("button", "Click me"),
      textInput("text", "Text")
    )

    server <- function(input, output) {
      observeEvent(input$button, {
        toggle("text")  # toggle is a shinyjs function
      })
    }

    shinyApp(ui, server)

This is how most Shiny apps should initialize `shinyjs` - by calling `useShinyjs()` near the top of the UI.

However, if you use shinyjs in any of the following cases:

- In Shiny dashboards (built using the `shinydashboard` package)
- In Shiny apps that use a `navbarPage` layout
- In interactive Rmd documents
- In Shiny apps that manually build the user interface with an HTML file or template (instead of using Shiny’s UI functions)

Then you should see the Including shinyjs in different types of apps document.

If your Shiny app doesn’t fall into any of these categories, then the above code sample should be enough to get your started with including shinyjs in your app.

## Basic use case - complete working example

See the shinyjs example app walk-through document for a step-by-step guide on how to add a variety of shinyjs features to a simple app in order to make it more user friendly.

## Calling your own JavaScript functions from R

You can also use `shinyjs` to add your own JavaScript functions that can be called from R as if they were regular R functions using `extendShinyjs`. This is only suitable for advanced users who are familiar with JavaScript and wish to facilitate the communication between R and JavaScript.

To learn about this feature and see how useful it can be, see the extendShinyjs: Calling your own JavaScript functions from R document.

## FAQ and extra tricks

There are several questions that pop up very frequently in my email or on StackOverflow about “How do I use shinyjs to do ___?” Here is a list of a few of these common questions with links to a solution that could be useful. Note that all of these require using `extendShinyjs()`.

- How do I show/hide the `shinydashboard` sidebar programmatically?
- How do I hide/disable a tab?
- How do I refresh the page?
- How do I call a JavaScript function from a different JavaScript library?
- How do I change the values of a `sliderInput`?
- How do I call JavaScript code and use the return value?

## Colour Picker input & addin

NOTE: As of August 2016, the colour picker functions are deprecated and have moved into a separate package `colourpicker`. Please use the `colourpicker` package instead of `shinyjs` in the future.

`shinyjs` has a `colourInput()` function that lets you add a colour picker widget to Shiny apps. There is also a colour picker RStudio addin (accessed through the Addins menu) and a gadget (accessed with the `colourPicker()` function) that can be used to easily select colours. The screenshot below is from the colour picker addin. You can also view a short GIF demo of the addin.

Colour picker screenshot

## More resources

This document is meant to serve as a high overview of shinyjs. There are three more documents provided in shinyjs to teach you various aspects of the package:

- Including shinyjs in different types of apps
- shinyjs example app walk-through
- extendShinyjs: Calling your own JavaScript functions from R

If you need help, I strongly suggest browsing the shinyjs tag on StackOverflow or asking your own question there. Of course you can also email me directly if you’re in desperate need of help, or open an issue for bugs.

## Motivation & alternatives using native Shiny

The initial release of this package was announced on my blog and discusses these topics.

## Contributions

If you have any suggestions or feedback, I would love to hear about it. You can either message me directly, open an issue if you want to request a feature/report a bug, or make a pull request if you can contribute.

I’d like to give special thanks to the Shiny developers, especially Joe Cheng for always answering all my Shiny questions.

Lastly, if you find shinyjs useful, please consider supporting me for the countless hours I’ve spent building, documenting, and supporting this package :)