Use ESM

Author: wooorm

.gitignore

@@ -1,6 +1,5 @@
 .DS_Store
 *.log
-.nyc_output/
 coverage/
 node_modules/
 test/jsx-*.js

.prettierignore

@@ -1,3 +1,2 @@
 coverage/
-*.json
 *.md

index.js

@@ -1,24 +1,21 @@
-'use strict'
-
-module.exports = x
-
 // Creating xast elements.
-function x(name, attributes) {
+export function x(name, attributes) {
   var node =
-    name == null
+    name === undefined || name === null
       ? {type: 'root', children: []}
-      : {type: 'element', name: name, attributes: {}, children: []}
+      : {type: 'element', name, attributes: {}, children: []}
   var index = 1
   var key
 
-  if (name != null && typeof name !== 'string') {
+  if (name !== undefined && name !== null && typeof name !== 'string') {
     throw new Error('Expected element name, got `' + name + '`')
   }
 
   // Handle props.
   if (attributes) {
     if (
-      name == null ||
+      name === undefined ||
+      name === null ||
       typeof attributes === 'string' ||
       typeof attributes === 'number' ||
       'length' in attributes
@@ -28,7 +25,12 @@ function x(name, attributes) {
     } else {
       for (key in attributes) {
         // Ignore nullish and NaN values.
-        if (attributes[key] != null && attributes[key] === attributes[key]) {
+        if (
+          attributes[key] !== undefined &&
+          attributes[key] !== null &&
+          (typeof attributes[key] !== 'number' ||
+            !Number.isNaN(attributes[key]))
+        ) {
           node.attributes[key] = String(attributes[key])
         }
       }
@@ -46,7 +48,7 @@ function x(name, attributes) {
 function addChild(nodes, value) {
   var index = -1
 
-  if (value == null) {
+  if (value === undefined || value === null) {
     // Empty.
   } else if (typeof value === 'string' || typeof value === 'number') {
     nodes.push({type: 'text', value: String(value)})

package.json

@@ -25,41 +25,38 @@
   "contributors": [
     "Titus Wormer <[email protected]> (https://wooorm.com)"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
+  "types": "types",
   "files": [
-    "index.js",
-    "types/index.d.ts"
+    "types/index.d.ts",
+    "index.js"
   ],
-  "types": "types",
   "dependencies": {
     "@types/xast": "^1.0.0"
   },
   "devDependencies": {
     "@babel/core": "^7.0.0",
     "@babel/plugin-syntax-jsx": "^7.0.0",
     "@babel/plugin-transform-react-jsx": "^7.0.0",
+    "astring": "^1.0.0",
     "buble": "^0.20.0",
-    "dtslint": "^4.0.0",
-    "nyc": "^15.0.0",
+    "c8": "^7.0.0",
+    "estree-util-build-jsx": "^2.0.0",
     "prettier": "^2.0.0",
     "remark-cli": "^9.0.0",
     "remark-preset-wooorm": "^8.0.0",
     "tape": "^5.0.0",
-    "unist-builder": "^2.0.0",
-    "xo": "^0.38.0"
+    "unist-builder": "^3.0.0",
+    "xo": "^0.39.0"
   },
   "scripts": {
     "generate": "node script/generate-jsx",
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
-    "test-api": "node test",
-    "test-coverage": "nyc --reporter lcov tape test/index.js",
-    "test-types": "dtslint types",
-    "test": "npm run generate && npm run format && npm run test-coverage && npm run test-types"
-  },
-  "nyc": {
-    "check-coverage": true,
-    "lines": 100,
-    "functions": 100,
-    "branches": 100
+    "test-api": "node test/index.js",
+    "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov node test/index.js",
+    "test": "npm run generate && npm run format && npm run test-coverage"
   },
   "prettier": {
     "tabWidth": 2,
@@ -71,20 +68,13 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false,
     "rules": {
-      "eqeqeq": [
-        "error",
-        "always",
-        {
-          "null": "ignore"
-        }
-      ],
-      "guard-for-in": "off",
-      "no-eq-null": "off",
-      "no-self-compare": "off",
-      "unicorn/prefer-number-properties": "off"
-    }
+      "no-var": "off",
+      "prefer-arrow-callback": "off"
+    },
+    "ignore": [
+      "types/"
+    ]
   },
   "remarkConfig": {
     "plugins": [

readme.md

@@ -13,6 +13,9 @@
 
 ## 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
@@ -22,8 +25,8 @@ npm install xastscript
 ## Use
 
 ```js
-var u = require('unist-builder')
-var x = require('xastscript')
+import {u} from 'unist-builder'
+import {x} from 'xastscript'
 
 // Children as an array:
 console.log(
@@ -188,8 +191,8 @@ If a [`Root`][root] node is given, its children are used instead.
 The example above (omitting the second) can then be written like so:
 
 ```jsx
-var u = require('unist-builder')
-var x = require('xastscript')
+import {u} from 'unist-builder'
+import {x} from 'xastscript'
 
 console.log(
   <album id={123}>
@@ -224,9 +227,8 @@ mode), and pass `pragma: 'x'` and `pragmaFrag: 'null'`.
 Babel also lets you configure this in a script:
 
 ```jsx
-/** @jsx x */
-/** @jsxFrag null */
-var x = require('xastscript')
+/** @jsx x @jsxFrag null */
+import {x} from 'xastscript'
 
 console.log(<music />)
 ```
@@ -241,7 +243,7 @@ TypeScript also lets you configure this in a script:
 ```tsx
 /** @jsx x */
 /** @jsxFrag null */
-import * as x from 'xastscript'
+import {x} from 'xastscript'
 
 console.log(<music />)
 ```

script/generate-jsx.js

@@ -1,23 +1,31 @@
-'use strict'
-
-var fs = require('fs')
-var path = require('path')
-var buble = require('buble')
-var babel = require('@babel/core')
+import fs from 'fs'
+import path from 'path'
+import babel from '@babel/core'
+import {Parser} from 'acorn'
+import acornJsx from 'acorn-jsx'
+import {generate} from 'astring'
+import {buildJsx} from 'estree-util-build-jsx'
 
 var doc = String(fs.readFileSync(path.join('test', 'jsx.jsx')))
 
 fs.writeFileSync(
-  path.join('test', 'jsx-buble.js'),
-  buble.transform(doc.replace(/'name'/, "'jsx (buble)'"), {
-    jsx: 'x',
-    jsxFragment: 'null'
-  }).code
+  path.join('test', 'jsx-build-jsx.js'),
+  generate(
+    buildJsx(
+      // @ts-ignore Acorn nodes are assignable to ESTree nodes.
+      Parser.extend(acornJsx()).parse(
+        doc.replace(/'name'/, "'jsx (estree-util-build-jsx, classic)'"),
+        {sourceType: 'module', ecmaVersion: 2021}
+      ),
+      {pragma: 'x', pragmaFrag: 'null'}
+    )
+  )
 )
 
 fs.writeFileSync(
   path.join('test', 'jsx-babel.js'),
-  babel.transform(doc.replace(/'name'/, "'jsx (babel)'"), {
+  // @ts-ignore Result always given.
+  babel.transform(doc.replace(/'name'/, "'jsx (babel, classic)'"), {
     plugins: [
       ['@babel/plugin-transform-react-jsx', {pragma: 'x', pragmaFrag: 'null'}]
     ]

test/core.js

@@ -1,7 +1,5 @@
-'use strict'
-
-var test = require('tape')
-var x = require('..')
+import test from 'tape'
+import {x} from '../index.js'
 
 test('xastscript', function (t) {
   t.equal(typeof x, 'function', 'should expose a function')
@@ -39,7 +37,7 @@ test('xastscript', function (t) {
   )
 
   t.deepEqual(
-    x('y', {a: null, b: undefined, c: NaN}),
+    x('y', {a: null, b: undefined, c: Number.NaN}),
     {type: 'element', name: 'y', attributes: {}, children: []},
     'should ignore null, undefined, and NaN attribute values'
   )

test/index.js

@@ -1,7 +1,5 @@
-'use strict'
-
 /* eslint-disable import/no-unassigned-import */
-require('./core')
-require('./jsx-babel')
-require('./jsx-buble')
+import './core.js'
+import './jsx-babel.js'
+import './jsx-build-jsx.js'
 /* eslint-enable import/no-unassigned-import */

test/jsx.jsx

@@ -1,8 +1,6 @@
-'use strict'
-
-var test = require('tape')
-var u = require('unist-builder')
-var x = require('..')
+import test from 'tape'
+import {u} from 'unist-builder'
+import {x} from '../index.js'
 
 test('name', function (t) {
   t.deepEqual(<a />, x('a'), 'should support a self-closing element')