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

@@ -1,19 +1,18 @@
-'use strict'
-
-module.exports = u
-
-function u(type, props, value) {
+export function u(type, props, value) {
   var node = {type: String(type)}
 
-  if (value == null && (typeof props !== 'object' || Array.isArray(props))) {
+  if (
+    (value === undefined || value === null) &&
+    (typeof props !== 'object' || Array.isArray(props))
+  ) {
     value = props
   } else {
     Object.assign(node, props)
   }
 
   if (Array.isArray(value)) {
     node.children = value
-  } else if (value != null) {
+  } else if (value !== undefined && value !== null) {
     node.value = String(value)
   }
 

package.json

@@ -30,15 +30,18 @@
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)",
     "Christian Murphy <christian.murphy.42@gmail.com>"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
+  "types": "types/index.d.ts",
   "files": [
     "index.js",
     "types/index.d.ts"
   ],
-  "types": "types/index.d.ts",
   "devDependencies": {
     "@types/mdast": "^3.0.0",
+    "c8": "^7.0.0",
     "dtslint": "^4.0.0",
-    "nyc": "^15.0.0",
     "prettier": "^2.0.0",
     "remark-cli": "^9.0.0",
     "remark-preset-wooorm": "^8.0.0",
@@ -47,17 +50,11 @@
   },
   "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-types": "dtslint types",
     "test": "npm run format && npm run test-coverage && npm run test-types"
   },
-  "nyc": {
-    "check-coverage": true,
-    "lines": 100,
-    "functions": 100,
-    "branches": 100
-  },
   "prettier": {
     "tabWidth": 2,
     "useTabs": false,
@@ -68,19 +65,9 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false,
-    "ignore": [
-      "types/"
-    ],
     "rules": {
-      "eqeqeq": [
-        "error",
-        "always",
-        {
-          "null": "ignore"
-        }
-      ],
-      "no-eq-null": "off"
+      "no-var": "off",
+      "prefer-arrow-callback": "off"
     }
   },
   "remarkConfig": {

readme.md

@@ -13,6 +13,9 @@ syntax.
 
 ## 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][]:
 
 ```bash
@@ -22,7 +25,7 @@ npm install unist-builder
 ## Use
 
 ```js
-var u = require('unist-builder')
+import {u} from 'unist-builder'
 
 var tree = u('root', [
   u('subtree', {id: 1}),
@@ -64,6 +67,9 @@ results in the following tree:
 
 ## API
 
+This package exports the following identifiers: `u`.
+There is no default export.
+
 ### `u(type[, props][, children|value])`
 
 Creates a node from `props`, `children`, and optionally `value`.

test.js

@@ -1,9 +1,7 @@
-'use strict'
+import test from 'tape'
+import {u} from './index.js'
 
-var test = require('tape')
-var u = require('.')
-
-test(function (t) {
+test('u', function (t) {
   t.deepEqual(
     u('root', [
       u('subtree', {id: 1}),