markdown (version 1.2)

markdownExtensions: Markdown extensions

Description

markdownExtensions returns a character vector listing all the extensions that are available in the markdown package.

Usage

markdownExtensions()

Value

A character vector listing all available extensions.

Details

They are all ON by default.

The Sundown library (upon which markdown is built) has optional support for several extensions described below. To turn these on globally in the markdown package, simply place some or all of them in a character vector and assign to the global option markdown.extensions like so:

options(markdown.extensions = markdownExtensions())

To override the global option, pass the extensions as an argument to one of the render functions, e.g.:

markdownToHTML(..., extensions = c('no_intra_emphasis'))

Description of all extensions:

'no_intra_emphasis'

skip markdown embedded in words.

'tables'

create HTML tables (see Examples).

'fenced_code'

treat text as verbatim when surrounded with begin and ending lines with three ~ or ` characters.

'autolink'

create HTML links from urls and email addresses.

'strikethrough'

create strikethroughs by surrounding text with ~~.

'lax_spacing'

allow HTML tags inside paragraphs without being surrounded by newlines.

'space_headers'

add a space between header hashes and the header itself.

'superscript'

translate ^ and subsequent text into HTML superscript.

'latex_math'

transforms all math equations into syntactically correct MathJax equations.

See the EXAMPLES section to see the output of each extension turned on or off.

See Also

markdownHTMLOptions

Examples

# List all available extensions:
markdownExtensions()

# To turn on all markdown extensions globally:
options(markdown.extensions = markdownExtensions())

# To turn off all markdown extensions globally:
options(markdown.extensions = NULL)

# The following examples are short, so we set the HTML option 'fragment_only'

options(markdown.HTML.options = "fragment_only")

# no_intra_emphasis example
cat(markdownToHTML(text = "foo_bar_function", extensions = c()))
cat(markdownToHTML(text = "foo_bar_function", extensions = c("no_intra_emphasis")))

# tables example (need 4 spaces at beginning of line here)
cat(markdownToHTML(text = "
    First Header  | Second Header
    ------------- | -------------
    Content Cell  | Content Cell
    Content Cell  | Content Cell
",
    extensions = c()))

# but not here
cat(markdownToHTML(text = "
First Header  | Second Header
------------- | -------------
Content Cell  | Content Cell
Content Cell  | Content Cell
",
    extensions = c("tables")))

# fenced_code example (need at least three leading ~ or `)
fenced_block <- function(text, x = "`", n = 3) {
    fence <- paste(rep(x, n), collapse = "")
    paste(fence, text, fence, sep = "")
}
cat(markdownToHTML(text = fenced_block("
preformatted text here without having to indent
first line.
"),
    extensions = c()))

cat(markdownToHTML(text = fenced_block("
preformatted text here without having to indent
first line.
"),
    extensions = c("fenced_code")))

# autolink example
cat(markdownToHTML(text = "https://www.r-project.org/", extensions = c()))
cat(markdownToHTML(text = "https://www.r-project.org/", extensions = c("autolink")))

# strikethrough example
cat(markdownToHTML(text = "~~awesome~~", extensions = c()))
cat(markdownToHTML(text = "~~awesome~~", extensions = c("strikethrough")))

# lax_spacing
cat(markdownToHTML(text = "
Embedding html without surrounding with empty newline.
_markdown_
extra text.
",
    extensions = c("")))
cat(markdownToHTML(text = "
Embedding html without surrounding with empty newline.
_markdown_
extra text.
",
    extensions = c("lax_spacing")))

# space_headers example
cat(markdownToHTML(text = "#A Header\neven though there is no space between # and A",
    extensions = c("")))
cat(markdownToHTML(text = "#Not A Header\nbecause there is no space between # and N",
    extensions = c("space_headers")))

# superscript example
cat(markdownToHTML(text = "2^10", extensions = c()))
cat(markdownToHTML(text = "2^10", extensions = c("superscript")))