Pandoc_metadata

get_pandoc_metadata <- function(file, to = "html") {
  template <- tempfile(fileext = ".json")
  json_out <- tempfile(fileext = ".json")
  xfun::write_utf8("$meta-json$", template)
  template_arg <- sprintf("--template=%s", template)
  rmarkdown::pandoc_convert(file, from = "markdown", to = to, 
                            options = c(template_arg), 
                            output = json_out)
  jsonlite::fromJSON(json_out)
}

test_rmd <- tempfile(fileext = ".Rmd")
rmarkdown::draft(test_rmd, template = "html-paged", package = "pagedown", edit = FALSE)
get_pandoc_metadata(test_rmd)