applause

Add an applause button to your web pages, blog posts, and Shiny apps. Based entirely on the awesome applause-button library by Colin Eberhardt.

The other goal of this project is to demonstrate how to use HTML dependencies with the htmltools package.

Installation

# install.packages("remotes")
remotes::install_github("gadenbuie/applause")

Demonstration and Usage

Skip library() and just add an applause button wherever you want one with

applause::button()

Check out the documentation to see applause::button() in action and for additional options.

Dev Log

Package Init

📑 Initial commit: d92bd3

library(usethis)
create_package("applause")
use_readme_md()

Create a directory in inst to hold the applause button dependencies. 📑 Changes: 8ee9f3

dir.create("inst/applause-button", recursive = TRUE)

Setup npm to import the JavaScript package

In a terminal, initialize an npm project in the package root to create a package.json. There are a few ways this can be done, but I prefer to have package.json and npm manage the JavaScript dependency. 📑 Changes: db0201

# In terminal, hit enter to accept most defaults, or change what you want
npm init

Use npm to install the applause-button dependencies. 📑 Changes: 90eb14

npm install applause-button

This step will install applause-button and it's related dependencies into node_modules/. It will also create a package-lock.json file that should be committed alongside package.json, but we don't want to commit the dependencies yet. In fact, we add those to build and git ignore files.

use_build_ignore("package.json")
use_build_ignore("package-lock.json")
use_build_ignore("node_modules/")
use_git_ignore("node_modules/")

Move the JavaScript dependencies into the R package

📑 Changes: 9c5500

Now we need to move the applause-button dependencies into our R package space. If you look inside node_modules/ you'll find the applause-button/ folder, which contains the library source and a dist/ directory where the JavaScript and CSS dependencies are stored. We need to copy these files from node_modules/applause-button/dist to inst/applause-button/.

I usually do this with npm so that it's handled by the JavaScript package manager and so that I don't forget to do this step. I use an npm package called copyfiles, which is added as a dev dependency.

npm install --save-dev copyfiles

Then I add the following to package.json in "scripts".

"scripts": {
  "copy": "copyfiles -f \"node_modules/applause-button/dist/applause-button.*\" inst/applause-button",
  "build": "npm run copy"
}

This creates two npm run scripts, a script for the copy step and a script for the build step. The build step at the moment just calls the copy step, but if we later decide to add more build steps, this format lets us add on easily.

To move the files where they need to be, run:

npm run build

Create html_dependency_applause()

Now we turn to building out the R package. First we depend on the htmltools package. 📑 Changes: a9fbf4

use_package("htmltools")

Then we create an html_dependency_applause() function in R/html_dependency.R. 📑 Changes: 453694

use_r("html_dependency")

The function looks like this:

html_dependency_applause <- function() {
  htmltools::htmlDependency(
    name = "applause-button",
    version = "3.3.2",
    package = "applause",
    src = "applause-button",
    script = "applause-button.js",
    stylesheet = "applause-button.css",
    all_files = FALSE
  )
}

The name of the dependency is applause-button because that's what it's called on npm, i.e. we ran npm install applause-button.
The version installed from npm was 3.3.2 (if we update the package later, we'll need to update this function).
The R package providing the dependency is called applause
The src directory where the files are located is applause-button, corresponding to inst/applause-button (the files in inst/ are installed in the package root directory when the package is installed.)
The script to be loaded is applause-button.js
The stylesheet to be loaded is applause-button.css
And just for safety, we set all_files = FALSE so that other files in this folder are included when the dependency is used.

The Applause button distribution files are also available via the unpkg CDN, so I updated src to include the URL to the directory containing the files. To specify both the local and remote locations of the distribution files, src in htmlDependency() accepts a named character vector, where the file item corresponds to the local path and the href item corresponds to the remote URL. 📑 Changes: 73d56a

src = c(
  file = "applause-button",
  href = "https://unpkg.com/applause-button@3.3.2/dist"
)

Create UI functions the provide the HTML

📑 Changes: 5f68db

The applause-button documentation page includes a section showing the HTML required to include an Applause button on your web page:

<head>
  <!-- add the button style & script -->
  <link rel="stylesheet" href="applause-button.css" />
  <script src="applause-button.js"></script>
</head>
<body>
  <!-- add the button! -->
  <applause-button style="width: 58px; height: 58px;"/>
</body>

The HTML dependency function we created above will provide htmltools with enough information to create the <link> and <script> tags that need to be included in the <head> of the page. Our next task is to provide a function that creates the HTML that appears in the page and to attach the html_dependency_applause() to that HTML.

The Applause button provides an interesting wrinkle at this step. Rather than using a classed <div>, the button uses a custom HTML tag: <applause-button>. So the first step is to create an appropriate tag. Again, from the [documentation], this tag can have the following attributes:

color, with a CSS color for the button
multiclap, a binary attribute that when "true" allows users to clap more than once
url, the URL used to track total claps, if unset the current referring page URL will be used
api, a URL for a custom Applause button back-end API.

use_r("button")

Following the above, I created a button() function that returns the custom element.

applause::button(color = "red", width = "33px")
## <applause-button style="width: 33px; height: 33px;" color="red"></applause-button>

The applause button at this point returns just the custom HTML tag, but doesn't include the dependencies. To include the applause button dependencies, we need to "attach" the html_dependency_applause() to the tag. The easiest way to do this is to return an htmltools::tagList() containing the HTML tags and the dependencies:

htmltools::tagList(
  button(),
  html_dependency_applause()
)

📑 Changes: 669d57

(Sidenote: at this point I'm beginning to question calling the function button(), but I think it's okay. This package will have only two exposed functions, and I'll recommend that most people call the fully qualified function name: applause::button().)

That's it!

The package now provides an HTML dependency and a custom Applause button component that can be dropped into an R Markdown document, a blogdown page, a Shiny app, or a xaringan presentation.

The last step is to fill out the DESCRIPTION and add a demonstration page and update the README!

👏 👏 👏