Use ESM

index.js

@@ -1,12 +1,8 @@
-'use strict'
+import syntax from 'micromark-extension-frontmatter'
+import fromMarkdown from 'mdast-util-frontmatter/from-markdown.js'
+import toMarkdown from 'mdast-util-frontmatter/to-markdown.js'
 
-var syntax = require('micromark-extension-frontmatter')
-var fromMarkdown = require('mdast-util-frontmatter/from-markdown')
-var toMarkdown = require('mdast-util-frontmatter/to-markdown')
-
-module.exports = frontmatter
-
-function frontmatter(options) {
+export default function remarkFrontmatter(options) {
   var data = this.data()
   add('micromarkExtensions', syntax(options))
   add('fromMarkdownExtensions', fromMarkdown(options))

package.json

@@ -26,11 +26,12 @@
     "Lars Trieloff <lars@trieloff.net>",
     "Max Kueng <me@maxkueng.com>"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
   "files": [
-    "index.js",
-    "types/index.d.ts"
+    "index.js"
   ],
-  "types": "types/index.d.ts",
   "dependencies": {
     "mdast-util-frontmatter": "^0.2.0",
     "micromark-extension-frontmatter": "^0.2.0"
@@ -67,6 +68,8 @@
     "prettier": true,
     "esnext": false,
     "rules": {
+      "no-var": "off",
+      "prefer-arrow-callback": "off",
       "unicorn/no-array-callback-reference": "off",
       "unicorn/prefer-optional-catch-binding": "off",
       "guard-for-in": "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 not = require('not')
-var hidden = require('is-hidden')
-var frontmatter = 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 not from 'not'
+import hidden from 'is-hidden'
+import frontmatter from '../index.js'
 
 var join = path.join
 var read = fs.readFileSync
@@ -66,7 +64,7 @@ test('frontmatter()', function (t) {
 })
 
 test('fixtures', function (t) {
-  var base = join(__dirname, 'fixtures')
+  var base = join('test', 'fixtures')
   var entries = dir(base).filter(not(hidden))
 
   t.plan(entries.length)