letter-press

letter-press

Print GitHub Markdown to PDF using headless Chrome.

Example

Print letter.md to dist/letter.pdf then log a completion message.

const letterpress = require('letter-press')
const letter = fs.readFileSync(path.join(__dirname, 'letter.md'))

letterpress.print('letter', letter)
  .then(() => console.log('🐈  done'))

Example: Print multiple letters using a template

Print letters to dist/*.pdf based on a Markdown template and some data (e.g. mailing list).

const letterpress = require('letter-press')

const letter = (sender, recipient) =>
`Dear ${recipient},

Here is some **bold text**. *Winky face*.

Yours sincerely,
${sender}
`
const list = [
  { id: 'letter1', sender: 'Your Secret Lesbian Admirer', recipient: 'John' }
  // ...
]

const press = await letterpress.launch()

const jobs = []
list.forEach(item => {
  const markdown = letter(item.sender, item.recipient)
  const job = press.print(item.id, markdown)
  jobs.push(job)
})

await Promise.all(jobs)
press.close()

API

letterpress.print(id, markdown, [opts])

Print the given markdown string to PDF.

Return: Promise

Writes the following files:
dist/id.html
dist/id.pdf

letterpress.launch([opts])

Launch a new Press.

Return: Promise of Press

Press.prototype.print(id, markdown, [opts])

Print the given markdown string to PDF.

Return: Promise of Press

Writes the following files:
dist/id.html
dist/id.pdf

The returned Promise resolves with the Press object so that calls can be chained (e.g. letterpress.launch then press.print then press.close). It is not necessary to wait for a print to resolve before calling print again - print scheduling is all handled under the hood.

Press.prototype.close()

Close this Press. Call after all prints have resolved or if an error is caught.

Options

These options can be set at launch and/or for each print.

opts.path Path to output folder. Default: dist

opts.quiet Only log when something goes awry. Default: false

opts.markdownIt Options passed to markdown-it: new MarkdownIt(opts). API

opts.markdownItPlugins An array of markdownItPlugins which will, in order be applied as a plugin for the markdown-it processing. For example, we can add the markdown-it-emoji and the markdown-it-math plugins to the markdown-it processing chain like so:

const emoji = require('markdown-it-emoji')
const mdMath = require('markdown-it-math')

const opts = {
  markdownItPlugins: [emoji, [mdMath, {}]]
}

opts.template Path to pug template file used when generating HTML. The template must contain a !=content, and may contain a !=title. Default: Template File

opts.pug Options passed to pug: pug.renderFile. API

opts.puppeteer Options passed to puppeteer: puppeteer.launch(opts). API

opts.pdf Options passed to puppeteer: page.pdf(opts). API

opts.toc Options passed to html-toc. API

opts.preprocessors An array of promise-returning functions that are expected to return the processed HTML. For instance, we can remove all the <style></style> tags from the html with the following preprocessor (using cheerio):

const cheerio = require('cheerio')

// Notice this is an `async` function, meaning it returns a Promise
const removeStyleFromBody = async html => {
  const $ = cheerio.load(html)
  $('body style').each(function (o) {
    $(this).remove()
  })
  return $.html() // Return all HTML
}

const opts = {
  preprocessors: [removeStyleFromBody]
}