How can I use JavaScript in code chunks of RMarkdown?

Question

Inspired by this answer, I would like to use for example this dataframe in R

input <- data.frame(text = c("a", "b", "c"), 
                    page_number = c(3, 5, 6))

to create a list out of the text, which links to the different page_numbers. The solution describes how to use JavaScript in Markdown but unfortunately not how to use it within code chunks (which is necessary to dynamically create a list).

Answer 1

I like to use the htmltools package for this kind of job.

You can create a HTML anchor with htmltools::a().
In order to create a link to slide #2, you need to write:

htmltools::a("text", href = "javascript:slidedeck.loadSlide(2)")

You can easily vectorize this expression. Don't forget to pass the resulting list to htmltools::tagList().
Here's a minimal Rmd with the example referenced in the question:

---
title: "Presentation"
output: ioslides_presentation
---

## Slide 1 - page 2

This is the first slide. With links to other slides:

```{r echo=FALSE}
input <- data.frame(text = c("a", "b", "c"), 
                    page_number = c(3, 5, 6))

htmltools::tagList(
  mapply(
    htmltools::a, 
    input$text, 
    href = sprintf("javascript:slidedeck.loadSlide(%i)", input$page_number), 
    SIMPLIFY = FALSE)
)
```
\

If you prefer the tidyverse:

```{r echo=FALSE, message=FALSE}
library(tidyverse)

tribble(
  ~text, ~page_number,
  "a",   3,
  "b",   5,
  "c",   6
) %>%
  transmute(
    text, 
    href = str_glue("javascript:slidedeck.loadSlide({page_number})")
  ) %>%
  pmap(~ htmltools::a(.x, href = .y)) %>%
  htmltools::tagList()
```

## Slide 2 - page 3

Text for slide 2

## Slide 3 - page 4

Text for slide 3

## Slide 4 - page 5

Text for slide 4

## Slide 5 - page 6

Text for slide 4