Use ESM

Author: wooorm

.gitignore

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

.prettierignore

@@ -1,3 +1,2 @@
 coverage/
-*.json
 *.md

index.js

@@ -1,12 +1,8 @@
-'use strict'
-
-var visit = require('unist-util-visit')
-
-module.exports = normalizeHeadings
+import {visit} from 'unist-util-visit'
 
 var max = 6
 
-function normalizeHeadings(tree) {
+export function normalizeHeadings(tree) {
   var multiple
   var first
   var title

package.json

@@ -28,34 +28,31 @@
     "Eugene Sharygin <eush77@gmail.com>",
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
   "files": [
     "index.js"
   ],
   "dependencies": {
-    "unist-util-visit": "^2.0.0"
+    "unist-util-visit": "^3.0.0"
   },
   "devDependencies": {
-    "nyc": "^15.0.0",
+    "c8": "^7.0.0",
     "prettier": "^2.0.0",
     "remark": "^13.0.0",
     "remark-cli": "^9.0.0",
     "remark-preset-wooorm": "^8.0.0",
     "tape": "^5.0.0",
-    "unist-util-remove-position": "^3.0.0",
-    "xo": "^0.38.0"
+    "unist-util-remove-position": "^4.0.0",
+    "xo": "^0.39.0"
   },
   "scripts": {
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
-    "test-api": "node test",
-    "test-coverage": "nyc --reporter lcov tape test/index.js",
+    "test-api": "node test/index.js",
+    "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov node 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,
@@ -66,7 +63,10 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false
+    "rules": {
+      "no-var": "off",
+      "prefer-arrow-callback": "off"
+    }
   },
   "remarkConfig": {
     "plugins": [

readme.md

@@ -17,6 +17,9 @@ contains some meta-information (usually title) about the document.
 
 ## 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
@@ -26,8 +29,8 @@ npm install mdast-normalize-headings
 ## Use
 
 ```js
-var u = require('unist-builder')
-var normalizeHeadings = require('mdast-normalize-headings')
+import {u} from 'unist-builder'
+import {normalizeHeadings} from 'mdast-normalize-headings'
 
 var tree = u('root', [
   u('heading', {depth: 1}, [u('text', 'title')]),
@@ -45,20 +48,29 @@ console.log(tree)
 Yields:
 
 ```js
-{ type: 'root',
-  children:
-   [ { type: 'heading', depth: 1, children: [Array] },
-     { type: 'heading', depth: 2, children: [Array] },
-     { type: 'heading', depth: 1, children: [Array] } ] }
-{ type: 'root',
-  children:
-   [ { type: 'heading', depth: 1, children: [Array] },
-     { type: 'heading', depth: 3, children: [Array] },
-     { type: 'heading', depth: 2, children: [Array] } ] }
+{
+  type: 'root',
+  children: [
+    {type: 'heading', depth: 1, children: [Array]},
+    {type: 'heading', depth: 2, children: [Array]},
+    {type: 'heading', depth: 1, children: [Array]}
+  ]
+}
+{
+  type: 'root',
+  children: [
+    {type: 'heading', depth: 1, children: [Array]},
+    {type: 'heading', depth: 3, children: [Array]},
+    {type: 'heading', depth: 2, children: [Array]}
+  ]
+}
 ```
 
 ## API
 
+This package exports the following identifiers: `normalizeHeadings`.
+There is no default export.
+
 ### `normalizeHeadings(tree)`
 
 Modifies [tree][] in-place.

test/index.js

@@ -1,11 +1,9 @@
-'use strict'
-
-var fs = require('fs')
-var path = require('path')
-var test = require('tape')
-var remark = require('remark')
-var remove = require('unist-util-remove-position')
-var normalizeHeadings = require('..')
+import fs from 'fs'
+import path from 'path'
+import test from 'tape'
+import remark from 'remark'
+import {removePosition} from 'unist-util-remove-position'
+import {normalizeHeadings} from '../index.js'
 
 test('Multiple top-level headings', function (t) {
   check(t, 'no-headings', 'No-op if there is no headings')
@@ -22,12 +20,12 @@ test('Level 7', function (t) {
 })
 
 function check(t, test, message) {
-  var input = fs.readFileSync(path.join(__dirname, 'fixture', test + '.in'))
-  var output = fs.readFileSync(path.join(__dirname, 'fixture', test + '.out'))
+  var input = fs.readFileSync(path.join('test', 'fixture', test + '.in'))
+  var output = fs.readFileSync(path.join('test', 'fixture', test + '.out'))
 
   t.deepEqual(
-    remove(normalizeHeadings(remark().parse(input)), true),
-    remove(remark().parse(output), true),
+    removePosition(normalizeHeadings(remark().parse(input)), true),
+    removePosition(remark().parse(output), true),
     message
   )
 }