Proper way to do dependency ingestion of js for Rmarkdown

Package development
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1

Hi,

I am developing a package that uses some js code in a RMarkdown document, or more precisely, in the html output of it. My problem is that I don't know how to ingest the javascript through a package function...

What I mean by that is the following: for a Shiny app, I can do it via a function like:

ingest_dependency <- function(){

  scripts_list <- c("js/script.js")

  htmltools::htmlDependency(
    name = "mypackage",
    version = utils::packageVersion("mypackage"),
    package = "mypackage",
    src = ".",
    script = scripts_list
  )

}

Then it is enough to call it from the ui and inst/js/script.js from the package is available. How can I do something similar in js (using a package function)?

2

I think you'll want to create a new output format function. The chapter Creating New Formats from the book R Markdown: The Definitive Guide provides some basic examples, but doesn't go so far as adding custom JS dependencies.

For a more realistic example, check out the function gitbook() from bookdown. It extends the output format rmarkdown::html_document() by passing its dependencies to the argument extra_dependencies (source). The dependencies are actually defined in a separate function: gitbook_dependency(). And that function adds the CSS/JS files in inst/resources/gitbook/.

So the main steps are something along the lines of:

  1. Save your supporting CSS/JS files somewhere in the inst/ directory of your package (the exact name doesn't matter)
  2. Use system.file() to pass your package's supporting files (using the name of the directory you chose in the previous step) to htmltools::htmlDependency()
  3. Create a custom output format function that calls an existing output format function (e.g. rmarkdown::html_document()) or starts a brand new one with rmarkdown::output_format(), passing the dependencies in the previous step to the argument extra_dependencies
3

Hi @jdblischak

Thanks for the detailed answer! I am not that familiar with Rmd options, but it does sound very similar to what I wanted.

I will take a look on the references. Thanks again!