Use ESM

.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

@@ -1,9 +1,7 @@
-'use strict'
+import {statistics} from 'vfile-statistics'
 
-const statistics = require('vfile-statistics')
-
-module.exports = (vfiles) =>
-  vfiles.map((vfile) => {
+export function toESLint(vfiles) {
+  return vfiles.map((vfile) => {
     const stats = statistics(vfile)
 
     return {
@@ -15,12 +13,13 @@ module.exports = (vfiles) =>
           ruleId: [x.source, x.ruleId].filter(Boolean).join(':') || null,
           line: x.line,
           column: x.column,
-          endLine: x.location.end.line,
-          endColumn: x.location.end.column,
+          endLine: x.position.end.line,
+          endColumn: x.position.end.column,
           message: x.reason
         }
       }),
       errorCount: stats.fatal,
       warningCount: stats.nonfatal
     }
   })
+}

package.json

@@ -30,30 +30,27 @@
   "files": [
     "index.js"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
   "dependencies": {
-    "vfile-statistics": "^1.1.1"
+    "vfile-statistics": "^2.0.0"
   },
   "devDependencies": {
-    "nyc": "^15.0.0",
+    "c8": "^7.0.0",
     "prettier": "^2.0.0",
     "remark-cli": "^9.0.0",
     "remark-preset-wooorm": "^8.0.0",
     "tape": "^5.0.0",
-    "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",
-    "test-api": "node test",
-    "test-coverage": "nyc --reporter lcov node test.js",
+    "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"
   },
-  "nyc": {
-    "check-coverage": true,
-    "lines": 100,
-    "functions": 100,
-    "branches": 100
-  },
   "prettier": {
     "tabWidth": 2,
     "useTabs": false,
@@ -63,11 +60,7 @@
     "trailingComma": "none"
   },
   "xo": {
-    "prettier": true,
-    "esnext": false,
-    "rules": {
-      "unicorn/prefer-optional-catch-binding": "off"
-    }
+    "prettier": true
   },
   "remarkConfig": {
     "plugins": [

readme.md

@@ -16,6 +16,9 @@ this module to display it using an ESLint formatter.
 
 ## 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
@@ -25,19 +28,24 @@ npm install vfile-to-eslint
 ## Use
 
 ```js
-const remark = require('remark')
-const recommended = require('remark-preset-lint-recommended')
-const eslintFormatterPretty = require('eslint-formatter-pretty')
-const vfileToEslint = require('vfile-to-eslint')
+import remark from 'remark'
+import recommended from 'remark-preset-lint-recommended'
+import eslintFormatterPretty from 'eslint-formatter-pretty'
+import {toESLint} from 'vfile-to-eslint'
 
 const file = remark()
   .use(recommended)
   .processSync('## Hello world!')
 
-console.log(eslintFormatterPretty(vfileToEslint([file])))
+console.log(eslintFormatterPretty(toESLint([file])))
 ```
 
-### `vfileToEslint(files)`
+## API
+
+This package exports the following identifiers: `toESLint`.
+There is no default export.
+
+### `toESLint(files)`
 
 Returns an `Object` that can be passed directly to an
 [ESLint formatter][eslint-formatter].

test.js

@@ -1,9 +1,9 @@
-var test = require('tape')
-var vfile = require('vfile')
-var toEslint = require('.')
+import test from 'tape'
+import {VFile} from 'vfile'
+import {toESLint} from './index.js'
 
-test('vfile-to-eslint', function (t) {
-  var file = vfile({path: '~/example.md'})
+test('toESLint', (t) => {
+  const file = new VFile({path: '~/example.md'})
 
   file.info('This is perfect', {line: 5, column: 3}, 'alpha:bravo')
 
@@ -21,9 +21,9 @@ test('vfile-to-eslint', function (t) {
         end: {line: 2, column: 8}
       }
     })
-  } catch (_) {}
+  } catch {}
 
-  t.deepEqual(toEslint([file]), [
+  t.deepEqual(toESLint([file]), [
     {
       filePath: '~/example.md',
       messages: [