Use ESM

index.js

@@ -1,10 +1,6 @@
-'use strict'
-
-var toString = require('nlcst-to-string')
-var visit = require('unist-util-visit')
-var convert = require('unist-util-is/convert')
-
-module.exports = sentenceSpacing
+import toString from 'nlcst-to-string'
+import visit from 'unist-util-visit'
+import convert from 'unist-util-is/convert.js'
 
 var sentence = convert('SentenceNode')
 var whiteSpace = convert('WhiteSpaceNode')
@@ -13,7 +9,7 @@ var source = 'retext-sentence-spacing'
 var ids = ['newline', 'space', 'double-space']
 var expected = ['\n', ' ', '  ']
 
-function sentenceSpacing(options) {
+export default function retextSentenceSpacing(options) {
   var preferred = (options || {}).preferred
 
   if (preferred === null || preferred === undefined || preferred === 'space') {

package.json

@@ -22,6 +22,9 @@
   "contributors": [
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
   "files": [
     "index.js"
   ],
@@ -37,7 +40,7 @@
     "remark-preset-wooorm": "^8.0.0",
     "retext": "^7.0.0",
     "tape": "^5.0.0",
-    "xo": "^0.37.0"
+    "xo": "^0.39.0"
   },
   "scripts": {
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
@@ -55,8 +58,9 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false,
     "rules": {
+      "no-var": "off",
+      "prefer-arrow-callback": "off",
       "unicorn/no-array-callback-reference": "off",
       "unicorn/prefer-type-error": "off"
     }

test.js

@@ -1,8 +1,6 @@
-'use strict'
-
-var test = require('tape')
-var retext = require('retext')
-var spacing = require('.')
+import test from 'tape'
+import retext from 'retext'
+import spacing from './index.js'
 
 var mixed = [
   'One sentence. Two sentences.',