Use ESM

Author: wooorm

.gitignore

@@ -1,6 +1,5 @@
-.DS_Store
-*.log
-.nyc_output/
 coverage/
 node_modules/
+.DS_Store
+*.log
 yarn.lock

.prettierignore

@@ -1,4 +1,3 @@
 coverage/
 *.html
-*.json
 *.md

from-markdown.js

@@ -1,2 +1,57 @@
-exports.fromMarkdown = require('./from-markdown.js')
-exports.toMarkdown = require('./to-markdown.js')
+import gfmAutolinkLiteralFromMarkdown from 'mdast-util-gfm-autolink-literal/from-markdown.js'
+import gfmAutolinkLiteralToMarkdown from 'mdast-util-gfm-autolink-literal/to-markdown.js'
+import gfmStrikethroughFromMarkdown from 'mdast-util-gfm-strikethrough/from-markdown.js'
+import gfmStrikethroughToMarkdown from 'mdast-util-gfm-strikethrough/to-markdown.js'
+import gfmTableFromMarkdown from 'mdast-util-gfm-table/from-markdown.js'
+import gfmTableToMarkdown from 'mdast-util-gfm-table/to-markdown.js'
+import gfmTaskListItemFromMarkdown from 'mdast-util-gfm-task-list-item/from-markdown.js'
+import gfmTaskListItemToMarkdown from 'mdast-util-gfm-task-list-item/to-markdown.js'
+
+var own = {}.hasOwnProperty
+
+export const gfmFromMarkdown = configure([
+  gfmAutolinkLiteralFromMarkdown,
+  gfmStrikethroughFromMarkdown,
+  gfmTableFromMarkdown,
+  gfmTaskListItemFromMarkdown
+])
+
+export function gfmToMarkdown(options) {
+  return {
+    extensions: [
+      gfmAutolinkLiteralToMarkdown,
+      gfmStrikethroughToMarkdown,
+      gfmTableToMarkdown(options),
+      gfmTaskListItemToMarkdown
+    ]
+  }
+}
+
+function configure(extensions) {
+  var config = {transforms: [], canContainEols: []}
+  var length = extensions.length
+  var index = -1
+
+  while (++index < length) {
+    extension(config, extensions[index])
+  }
+
+  return config
+}
+
+function extension(config, extension) {
+  var key
+  var left
+  var right
+
+  for (key in extension) {
+    left = own.call(config, key) ? config[key] : (config[key] = {})
+    right = extension[key]
+
+    if (key === 'canContainEols' || key === 'transforms') {
+      config[key] = [].concat(left, right)
+    } else {
+      Object.assign(left, right)
+    }
+  }
+}

index.js

@@ -30,10 +30,11 @@
   "contributors": [
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
   "files": [
-    "from-markdown.js",
-    "index.js",
-    "to-markdown.js"
+    "index.js"
   ],
   "dependencies": {
     "mdast-util-gfm-autolink-literal": "^0.1.0",
@@ -43,32 +44,26 @@
     "mdast-util-to-markdown": "^0.6.1"
   },
   "devDependencies": {
+    "c8": "^7.0.0",
     "github-slugger": "^1.0.0",
-    "hast-util-to-html": "^7.0.0",
+    "hast-util-to-html": "^8.0.0",
     "mdast-util-from-markdown": "^0.8.0",
-    "mdast-util-to-hast": "^10.0.0",
+    "mdast-util-to-hast": "^11.0.0",
     "micromark-extension-gfm": "^0.3.0",
     "node-fetch": "^2.0.0",
-    "nyc": "^15.0.0",
     "prettier": "^2.0.0",
     "remark-cli": "^9.0.0",
     "remark-preset-wooorm": "^8.0.0",
     "tape": "^5.0.0",
-    "xo": "^0.38.0"
+    "xo": "^0.39.0"
   },
   "scripts": {
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
     "crawl": "node script/crawl-tests",
-    "test-api": "node test",
-    "test-coverage": "nyc --reporter lcov tape test/index.js",
+    "test-api": "node --conditions development test/index.js",
+    "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov node --conditions development test/index.js",
     "test": "npm run format && npm run test-coverage"
   },
-  "nyc": {
-    "check-coverage": true,
-    "lines": 100,
-    "functions": 100,
-    "branches": 100
-  },
   "prettier": {
     "tabWidth": 2,
     "useTabs": false,
@@ -79,8 +74,9 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false,
     "rules": {
+      "no-var": "off",
+      "prefer-arrow-callback": "off",
       "guard-for-in": "off",
       "unicorn/prefer-optional-catch-binding": "off"
     }

package.json

@@ -30,6 +30,9 @@ Alternatively, the extensions can be used separately:
 
 ## Install
 
+This package is [ESM only](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c):
+Node 12+ is needed to use it and it must be `import`ed instead of `require`d.
+
 [npm][]:
 
 ```sh
@@ -212,13 +215,13 @@ Now, running `node example` yields:
 
 ## API
 
-### `gfm.fromMarkdown`
+This package exports the following identifier: `gfmFromMarkdown`,
+`gfmToMarkdown`.
+There is no default export.
 
-### `gfm.toMarkdown(options?)`
+### `gfmFromMarkdown`
 
-> Note: the separate extensions are also available at
-> `mdast-util-gfm/from-markdown` and
-> `mdast-util-gfm/to-markdown`.
+### `gfmToMarkdown(options?)`
 
 Support GFM.
 The exports of `fromMarkdown` is an extension for

readme.md

@@ -1,8 +1,6 @@
-'use strict'
-
-var fs = require('fs')
-var path = require('path')
-var fetch = require('node-fetch')
+import fs from 'fs'
+import path from 'path'
+import fetch from 'node-fetch'
 
 fetch(
   'https://api.github.com/repos/micromark/micromark-extension-gfm/contents/test/spec.json',

script/crawl-tests.js

@@ -1,14 +1,15 @@
-var fs = require('fs')
-var path = require('path')
-var test = require('tape')
-var slug = require('github-slugger').slug
-var toHast = require('mdast-util-to-hast')
-var toHtml = require('hast-util-to-html')
-var fromMarkdown = require('mdast-util-from-markdown')
-var toMarkdown = require('mdast-util-to-markdown')
-var syntax = require('micromark-extension-gfm')()
-var gfm = require('../index.js')
-var spec = require('./spec.json')
+import fs from 'fs'
+import path from 'path'
+import test from 'tape'
+import Slugger from 'github-slugger'
+import {toHast} from 'mdast-util-to-hast'
+import {toHtml} from 'hast-util-to-html'
+import fromMarkdown from 'mdast-util-from-markdown'
+import toMarkdown from 'mdast-util-to-markdown'
+import gfm from 'micromark-extension-gfm'
+import {gfmFromMarkdown, gfmToMarkdown} from '../index.js'
+
+const spec = JSON.parse(fs.readFileSync(path.join('test', 'spec.json')))
 
 test('markdown -> mdast', function (t) {
   const files = spec.filter(
@@ -18,19 +19,19 @@ test('markdown -> mdast', function (t) {
 
   while (++index < files.length) {
     const example = files[index]
-    var category = slug(example.category)
+    var category = Slugger.slug(example.category)
     var name = index + '-' + category
-    var fixtureHtmlPath = path.join(__dirname, name + '.html')
-    var fixtureMarkdownPath = path.join(__dirname, name + '.md')
+    var fixtureHtmlPath = path.join('test', name + '.html')
+    var fixtureMarkdownPath = path.join('test', name + '.md')
     var fixtureHtml
     var fixtureMarkdown
     var mdast
     var html
     var md
 
     mdast = fromMarkdown(example.input, {
-      extensions: [syntax],
-      mdastExtensions: [gfm.fromMarkdown]
+      extensions: [gfm()],
+      mdastExtensions: [gfmFromMarkdown]
     })
 
     html = toHtml(toHast(mdast, {allowDangerousHtml: true, commonmark: true}), {
@@ -45,7 +46,7 @@ test('markdown -> mdast', function (t) {
       fixtureHtml = example.output.slice(0, -1)
     }
 
-    md = toMarkdown(mdast, {extensions: [gfm.toMarkdown()]})
+    md = toMarkdown(mdast, {extensions: [gfmToMarkdown()]})
 
     try {
       fixtureMarkdown = String(fs.readFileSync(fixtureMarkdownPath))