How to Add a CSS Class to a Code Chunk in R Markdown: A Comparison of Methods

How to Add a CSS Class to a Specific Code Chunk in RMarkdown

When working with RMarkdown documents, you may want to enhance the appearance of certain code chunks by adding CSS classes to them. This allows you to control the visual presentation of these code elements.

Is it possible to add a CSS class to a code chunk?

Yes, you can add a CSS class to a specific code chunk using the following syntax:

summary(cars)

This syntax will apply the CSS class "myClass" to the code chunk labeled 'cars'.

Previous Method Using Fenced Code Attributes

Before the introduction of knitr v.1.16, there was a workaround involving the fenced_code_attributes Pandoc extension. This allowed for the addition of HTML classes to the

 tag using an output hook:</p>
<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false"><code class="r">knitr::knit_hooks$set(source = function(x, options) {
  return(paste0(
    "```{.r",
    ifelse(is.null(options$class),
      "", 
      paste0(" .", gsub(" ", " .", options$class))
    ),
    "}\n",
    x,
    "\n```"
  ))
})</code>