Add a script to convert HTML to PDF

This could be used, for example, to render a PDF version of the shiny
new Git Cheat Sheet.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

script/html-to-pdf.js

@@ -0,0 +1,51 @@
+#!/usr/bin/env node
+
+const fs = require('fs')
+const path = require('path')
+const { chromium } = require('playwright')
+
+const htmlToPDF = async (htmlPath, options) => {
+  if (!htmlPath.endsWith('.html')) {
+    throw new Error(`Input file must have the '.html' extension: ${htmlPath}`)
+  }
+  if (!fs.existsSync(htmlPath)) {
+    throw new Error(`Input file does not exist: ${htmlPath}`)
+  }
+  const outputPath = htmlPath.replace(/\.html$/, '.pdf')
+  if (!options.force && fs.existsSync(outputPath)) {
+    throw new Error(`Output file already exists: ${outputPath}`)
+  }
+
+  const browser = await chromium.launch({ channel: 'chrome' })
+  const page = await browser.newPage()
+
+  await page.goto(
+    `file://${path.isAbsolute(htmlPath) ? htmlPath : path.join(process.cwd(), htmlPath)}`, {
+      waitUntil: 'load'
+    }
+  )
+  await page.pdf({
+    path: outputPath,
+    format: 'A4',
+    margin: { top: '1cm', bottom: '1cm', left: '1cm', right: '1cm' },
+  })
+  await browser.close()
+}
+
+const args = process.argv.slice(2)
+const options = {}
+while (args?.[0].startsWith('-')) {
+  const arg = args.shift()
+  if (arg === '--force' || arg === '-f') options.force = true
+  else throw new Error(`Unknown argument: ${arg}`)
+}
+
+if (args.length !== 1) {
+  process.stderr.write('Usage: html-to-pdf.js [--force] <input-file.html>\n')
+  process.exit(1)
+}
+
+htmlToPDF(args[0], options).catch(e => {
+  process.stderr.write(`${e.stack}\n`)
+  process.exit(1)
+})