Use ESM

index.js

@@ -1,14 +1,10 @@
-'use strict'
-
-var syntax = require('micromark-extension-gfm')
-var fromMarkdown = require('mdast-util-gfm/from-markdown')
-var toMarkdown = require('mdast-util-gfm/to-markdown')
+import syntax from 'micromark-extension-gfm'
+import fromMarkdown from 'mdast-util-gfm/from-markdown.js'
+import toMarkdown from 'mdast-util-gfm/to-markdown.js'
 
 var warningIssued
 
-module.exports = gfm
-
-function gfm(options) {
+export default function remarkGfm(options) {
   var data = this.data()
 
   // Old remark.

package.json

@@ -27,9 +27,10 @@
   "contributors": [
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
-  "types": "types/index.d.ts",
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
   "files": [
-    "types/index.d.ts",
     "index.js"
   ],
   "dependencies": {
@@ -69,6 +70,8 @@
     "prettier": true,
     "esnext": false,
     "rules": {
+      "no-var": "off",
+      "prefer-arrow-callback": "off",
       "unicorn/no-fn-reference-in-iterator": "off",
       "unicorn/prefer-optional-catch-binding": "off"
     }

test/index.js

@@ -1,14 +1,12 @@
-'use strict'
-
-var fs = require('fs')
-var path = require('path')
-var test = require('tape')
-var vfile = require('to-vfile')
-var unified = require('unified')
-var remark = require('remark')
-var hidden = require('is-hidden')
-var stringWidth = require('string-width')
-var gfm = require('..')
+import fs from 'fs'
+import path from 'path'
+import test from 'tape'
+import vfile from 'to-vfile'
+import unified from 'unified'
+import remark from 'remark'
+import hidden from 'is-hidden'
+import stringWidth from 'string-width'
+import gfm from '../index.js'
 
 test('gfm()', function (t) {
   t.doesNotThrow(function () {
@@ -23,7 +21,7 @@ test('gfm()', function (t) {
 })
 
 test('fixtures', function (t) {
-  var base = path.join(__dirname, 'fixtures')
+  var base = path.join('test', 'fixtures')
   var entries = fs.readdirSync(base)
   var index = -1
   var file