Use ESM

.gitignore

@@ -1,8 +1,5 @@
 .DS_Store
 *.log
-.nyc_output/
 coverage/
 node_modules/
-vfile-statistics.js
-vfile-statistics.min.js
 yarn.lock

.prettierignore

@@ -1,5 +1,2 @@
 coverage/
-vfile-statistics.js
-vfile-statistics.min.js
-*.json
 *.md

index.js

@@ -1,9 +1,5 @@
-'use strict'
-
-module.exports = statistics
-
 // Get stats for a file, list of files, or list of messages.
-function statistics(value) {
+export function statistics(value) {
   var result = {true: 0, false: 0, null: 0}
 
   if (value) {
@@ -37,7 +33,9 @@ function statistics(value) {
 
     while (++index < messages.length) {
       result[
-        messages[index].fatal == null ? null : Boolean(messages[index].fatal)
+        messages[index].fatal === undefined || messages[index].fatal === null
+          ? null
+          : Boolean(messages[index].fatal)
       ]++
     }
   }

package.json

@@ -25,34 +25,26 @@
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)",
     "Brendan Abbott <brendan.abbott@temando.com>"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
   "files": [
     "index.js"
   ],
   "devDependencies": {
-    "browserify": "^17.0.0",
-    "nyc": "^15.0.0",
+    "c8": "^7.7.2",
     "prettier": "^2.0.0",
     "remark-cli": "^9.0.0",
     "remark-preset-wooorm": "^8.0.0",
     "tape": "^5.0.0",
-    "tinyify": "^3.0.0",
-    "vfile": "^4.0.0",
-    "xo": "^0.38.0"
+    "vfile": "^5.0.0",
+    "xo": "^0.39.0"
   },
   "scripts": {
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
-    "build-bundle": "browserify . -s vfileStatistics -o vfile-statistics.js",
-    "build-mangle": "browserify . -s vfileStatistics -o vfile-statistics.min.js -p tinyify",
-    "build": "npm run build-bundle && npm run build-mangle",
-    "test-api": "node test",
-    "test-coverage": "nyc --reporter lcov tape test.js",
-    "test": "npm run format && npm run build && npm run test-coverage"
-  },
-  "nyc": {
-    "check-coverage": true,
-    "lines": 100,
-    "functions": 100,
-    "branches": 100
+    "test-api": "node test.js",
+    "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov node test.js",
+    "test": "npm run format && npm run test-coverage"
   },
   "prettier": {
     "tabWidth": 2,
@@ -64,15 +56,10 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false,
     "rules": {
-      "eqeqeq": "off",
-      "no-eq-null": "off",
-      "unicorn/prefer-optional-catch-binding": "off"
-    },
-    "ignores": [
-      "vfile-statistics.js"
-    ]
+      "no-var": "off",
+      "prefer-arrow-callback": "off"
+    }
   },
   "remarkConfig": {
     "plugins": [

readme.md

@@ -12,6 +12,9 @@ Count [vfile][] messages per category (fatal, warn, info, nonfatal and total).
 
 ## 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
@@ -21,10 +24,10 @@ npm install vfile-statistics
 ## Use
 
 ```js
-var vfile = require('vfile')
-var statistics = require('vfile-statistics')
+import {VFile} from 'vfile'
+import {statistics} from 'vfile-statistics'
 
-var file = vfile({path: '~/example.md'})
+var file = new VFile({path: '~/example.md'})
 
 file.message('This could be better')
 file.message('That could be better')
@@ -46,6 +49,9 @@ Yields:
 
 ## API
 
+This package exports the following identifiers: `statistics`.
+There is no default export.
+
 ### `statistics(file)`
 
 Pass a [vfile][], list of vfiles, or a list of messages (`file.messages`), get

test.js

@@ -1,12 +1,10 @@
-'use strict'
-
-var test = require('tape')
-var vfile = require('vfile')
-var statistics = require('.')
+import test from 'tape'
+import {VFile} from 'vfile'
+import {statistics} from './index.js'
 
 test('statistics()', function (t) {
-  var file = vfile()
-  var other = vfile()
+  var file = new VFile()
+  var other = new VFile()
 
   t.deepEqual(statistics(), {fatal: 0, nonfatal: 0, warn: 0, info: 0, total: 0})
 
@@ -74,7 +72,7 @@ test('statistics()', function (t) {
 
   try {
     file.fail('Again')
-  } catch (_) {}
+  } catch {}
 
   t.deepEqual(statistics(file), {
     fatal: 1,