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

@@ -1,10 +1,6 @@
-'use strict'
-
-module.exports = attachComments
-
 var push = [].push
 
-function attachComments(tree, comments) {
+export function attachComments(tree, comments) {
   walk(tree, {comments: comments.concat().sort(compare), index: 0})
   return tree
 }

package.json

@@ -24,13 +24,16 @@
   "contributors": [
     "Titus Wormer <[email protected]> (https://wooorm.com)"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
   "files": [
     "index.js"
   ],
   "devDependencies": {
     "acorn": "^8.0.0",
+    "c8": "^7.0.0",
     "estree-walker": "^2.0.0",
-    "nyc": "^15.0.0",
     "prettier": "^2.0.0",
     "recast": "^0.20.0",
     "remark-cli": "^9.0.0",
@@ -40,8 +43,8 @@
   },
   "scripts": {
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
-    "test-api": "node test",
-    "test-coverage": "nyc --reporter lcov tape 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"
   },
   "prettier": {
@@ -54,20 +57,15 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false,
     "rules": {
+      "no-var": "off",
+      "prefer-arrow-callback": "off",
       "guard-for-in": "off",
       "max-depth": "off",
       "unicorn/explicit-length-check": "off",
       "unicorn/prefer-number-properties": "off"
     }
   },
-  "nyc": {
-    "check-coverage": true,
-    "lines": 100,
-    "functions": 100,
-    "branches": 100
-  },
   "remarkConfig": {
     "plugins": [
       "preset-wooorm"

readme.md

@@ -14,6 +14,9 @@ tree.
 
 ## Install
 
+This package is ESM only: Node 12+ is needed to use it and it must be `import`ed
+instead of `require`d.
+
 [npm][]:
 
 ```sh
@@ -31,9 +34,9 @@ Say we have this weird `code`:
 And our script, `example.js`, looks as follows:
 
 ```js
-var acorn = require('acorn')
-var recast = require('recast')
-var attachComments = require('estree-util-attach-comments')
+import * as acorn from 'acorn'
+import recast from 'recast'
+import {attachComments} from 'estree-util-attach-comments'
 
 var comments = []
 var tree = acorn.parse(code, {ecmaVersion: 2020, onComment: comments})
@@ -68,6 +71,9 @@ And, some of these weird comments are off, but they’re pretty close.
 
 ## API
 
+This package exports the following identifiers: `attachComment`.
+There is no default export.
+
 ### `attachComment(tree, comments)`
 
 Attach semistandard estree comment nodes to the tree.

test.js

@@ -1,10 +1,8 @@
-'use strict'
-
-var test = require('tape')
-var acorn = require('acorn')
-var recast = require('recast')
-var walk = require('estree-walker').walk
-var attachComments = require('.')
+import test from 'tape'
+import {parse as acornParse} from 'acorn'
+import recast from 'recast'
+import {walk} from 'estree-walker'
+import {attachComments} from './index.js'
 
 test('estree-attach-comments (recast)', function (t) {
   t.equal(
@@ -75,7 +73,7 @@ test('estree-attach-comments (recast)', function (t) {
   )
 
   var comments = []
-  var tree = acorn.parse('/* 1 */ a /* 2 */ + /* 3 */ 1', {
+  var tree = acornParse('/* 1 */ a /* 2 */ + /* 3 */ 1', {
     ecmaVersion: 2020,
     onComment: comments
   })
@@ -89,7 +87,7 @@ test('estree-attach-comments (recast)', function (t) {
   )
 
   comments = []
-  tree = acorn.parse('/* 1 */ a /* 2 */ + /* 3 */ 1', {
+  tree = acornParse('/* 1 */ a /* 2 */ + /* 3 */ 1', {
     ecmaVersion: 2020,
     onComment: comments
   })
@@ -103,7 +101,7 @@ test('estree-attach-comments (recast)', function (t) {
   )
 
   comments = []
-  tree = acorn.parse('/* 1 */ a /* 2 */ + /* 3 */ 1', {
+  tree = acornParse('/* 1 */ a /* 2 */ + /* 3 */ 1', {
     ecmaVersion: 2020,
     ranges: true,
     onComment: comments
@@ -118,7 +116,7 @@ test('estree-attach-comments (recast)', function (t) {
   )
 
   comments = []
-  tree = acorn.parse('/* 1 */ a /* 2 */ + /* 3 */ 1', {
+  tree = acornParse('/* 1 */ a /* 2 */ + /* 3 */ 1', {
     ecmaVersion: 2020,
     locations: true,
     onComment: comments
@@ -137,13 +135,13 @@ test('estree-attach-comments (recast)', function (t) {
 
 function parse(doc) {
   var comments = []
-  var tree = acorn.parse(doc, {ecmaVersion: 2020, onComment: comments})
+  var tree = acornParse(doc, {ecmaVersion: 2020, onComment: comments})
   return [tree, comments]
 }
 
 function removePositions(value) {
   walk(value, {
-    enter: function (node) {
+    enter(node) {
       delete node.start
       delete node.end
     }