A general-purpose link checker for R Markdown and Quarto projects https://nanx.me/blog/post/rmarkdown-quarto-link-checker/

check-url.R

#' Flatten copy
#'
#' @param from Source directory path.
#' @param to Destination directory path.
#'
#' @return Destination directory path.
#'
#' @details
#' Copy all `.Rmd`, `.qmd`, and `.md` files from source to destination,
#' rename the `.qmd` and `.md` files with an additional `.Rmd` extension,
#' and get a flat destination structure with path-preserving file names.
flatten_copy <- function(from, to) {
  rmd <- list.files(from, pattern = "\\.Rmd$", recursive = TRUE, full.names = TRUE)
  xmd <- list.files(from, pattern = "\\.qmd$|\\.md$", recursive = TRUE, full.names = TRUE)

  src <- c(rmd, xmd)
  dst <- c(rmd, paste0(xmd, ".Rmd"))

  # Remove starting `./` (if any)
  dst <- gsub("^\\./", replacement = "", x = dst)
  # Replace the forward slash in path with Unicode big solidus
  dst <- gsub("/", replacement = "\u29F8", x = dst)

  file.copy(src, to = file.path(to, dst))

  invisible(to)
}

#' Check URLs in an R Markdown or Quarto project
#'
#' @param input Path to the project directory.
#'
#' @return URL checking results from `urlchecker::url_check()`
#' for all `.Rmd`, `.qmd`, and `.md` files in the project.
#'
#' @details
#' The `tools::pkgVignettes()$docs` call in urlchecker requires
#' two core criteria (`VignetteBuilder` and `VignetteEngine`)
#' to recognize `.Rmd` files as package vignettes.
check_url <- function(input = ".") {
  # Create a source package directory
  pkg <- tempfile()
  dir.create(pkg)

  # Flatten copy relevant files
  vig <- file.path(pkg, "vignettes")
  dir.create(vig)
  flatten_copy(input, vig)

  # Create a minimal DESCRIPTION file
  write("VignetteBuilder: knitr", file = file.path(pkg, "DESCRIPTION"))

  # Make the copied files look like vignettes
  lapply(
    list.files(vig, full.names = TRUE),
    function(x) {
      write(
        "---\nvignette: >\n  %\\VignetteEngine{knitr::rmarkdown}\n---",
        file = x, append = TRUE
      )
    }
  )

  urlchecker::url_check(pkg)
}

check_url()

@Nowosad Thanks! If not specifically claimed, the code samples shared on my blog are licensed under Creative Commons CC0 1.0 Universal (CC0 1.0), i.e. public domain, just like how the code is licensed in the Mastering Shiny book.

Great -- thanks!