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 +1,15 @@
-'use strict'
-
-module.exports = buildJsx
-
-var walk = require('estree-walker').walk
-var isIdentifierName = require('estree-util-is-identifier-name').name
+import {walk} from 'estree-walker'
+import {name as isIdentifierName} from 'estree-util-is-identifier-name'
 
 var regex = /@(jsx|jsxFrag|jsxImportSource|jsxRuntime)\s+(\S+)/g
 
-function buildJsx(tree, options) {
+export function buildJsx(tree, options) {
   var settings = options || {}
   var automatic = settings.runtime === 'automatic'
   var annotations = {}
   var imports = {}
 
-  walk(tree, {enter: enter, leave: leave})
+  walk(tree, {enter, leave})
 
   return tree
 
@@ -109,10 +105,10 @@ function buildJsx(tree, options) {
         })
       }
 
-      if (specifiers.length) {
+      if (specifiers.length > 0) {
         node.body.unshift({
           type: 'ImportDeclaration',
-          specifiers: specifiers,
+          specifiers,
           source: {
             type: 'Literal',
             value:
@@ -184,7 +180,7 @@ function buildJsx(tree, options) {
       // in them and what’s spread in.
       while (++index < attributes.length) {
         if (attributes[index].type === 'JSXSpreadAttribute') {
-          if (fields.length) {
+          if (fields.length > 0) {
             objects.push({type: 'ObjectExpression', properties: fields})
             fields = []
           }
@@ -218,7 +214,7 @@ function buildJsx(tree, options) {
       )
     }
 
-    if (automatic && children.length) {
+    if (automatic && children.length > 0) {
       fields.push({
         type: 'Property',
         key: {type: 'Identifier', name: 'children'},
@@ -232,7 +228,7 @@ function buildJsx(tree, options) {
       parameters = children
     }
 
-    if (fields.length) {
+    if (fields.length > 0) {
       objects.push({type: 'ObjectExpression', properties: fields})
     }
 
@@ -247,7 +243,7 @@ function buildJsx(tree, options) {
         callee: toMemberExpression('Object.assign'),
         arguments: objects
       }
-    } else if (objects.length) {
+    } else if (objects.length > 0) {
       props = objects[0]
     }
 
@@ -269,7 +265,7 @@ function buildJsx(tree, options) {
     // Classic.
     else {
       // There are props or children.
-      if (props || parameters.length) {
+      if (props || parameters.length > 0) {
         parameters.unshift(props || {type: 'Literal', value: null})
       }
 
@@ -281,11 +277,7 @@ function buildJsx(tree, options) {
     parameters.unshift(name)
 
     this.replace(
-      create(node, {
-        type: 'CallExpression',
-        callee: callee,
-        arguments: parameters
-      })
+      create(node, {type: 'CallExpression', callee, arguments: parameters})
     )
   }
 }
@@ -312,7 +304,7 @@ function toProperty(node) {
   return create(node, {
     type: 'Property',
     key: toIdentifier(node.name),
-    value: value,
+    value,
     kind: 'init'
   })
 }

package.json

@@ -31,17 +31,21 @@
   "contributors": [
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
   "files": [
     "index.js"
   ],
   "dependencies": {
-    "estree-util-is-identifier-name": "^1.0.0",
-    "estree-walker": "^2.0.0"
+    "estree-util-is-identifier-name": "^2.0.0",
+    "estree-walker": "^3.0.0"
   },
   "devDependencies": {
     "acorn": "^8.0.0",
     "acorn-jsx": "^5.0.0",
     "astring": "^1.0.0",
+    "c8": "^7.6.0",
     "escodegen": "^2.0.0",
     "nyc": "^15.0.0",
     "prettier": "^2.0.0",
@@ -53,8 +57,8 @@
   },
   "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": {
@@ -67,20 +71,11 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false,
     "rules": {
-      "guard-for-in": "off",
-      "max-depth": "off",
-      "unicorn/explicit-length-check": "off",
-      "unicorn/prefer-number-properties": "off"
+      "no-var": "off",
+      "prefer-arrow-callback": "off"
     }
   },
-  "nyc": {
-    "check-coverage": true,
-    "lines": 100,
-    "functions": 100,
-    "branches": 100
-  },
   "remarkConfig": {
     "plugins": [
       "preset-wooorm"

readme.md

@@ -16,6 +16,9 @@ So let’s make that two implementations.
 
 ## 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
@@ -27,7 +30,7 @@ npm install estree-util-build-jsx
 Say we have the following file, `example.jsx`:
 
 ```js
-var x = require('xastscript')
+import x from 'xastscript'
 
 console.log(
   <album id={123}>
@@ -49,25 +52,28 @@ console.log(
 And our script, `example.js`, looks as follows:
 
 ```js
-var fs = require('fs')
-var acorn = require('acorn')
-var jsx = require('acorn-jsx')
-var astring = require('astring')
-var build = require('estree-util-build-jsx')
+import fs from 'fs'
+import {Parser} from 'acorn'
+import jsx from 'acorn-jsx'
+import astring from 'astring'
+import {buildJsx} from 'estree-util-build-jsx'
 
 var doc = fs.readFileSync('example.jsx')
 
-var tree = acorn.Parser.extend(jsx()).parse(doc)
+var tree = Parser.extend(jsx()).parse(doc, {
+  sourceType: 'module',
+  ecmaVersion: 2020
+})
 
-build(tree, {pragma: 'x', pragmaFrag: 'null'})
+buildJsx(tree, {pragma: 'x', pragmaFrag: 'null'})
 
 console.log(astring.generate(tree))
 ```
 
 Now, running `node example` yields:
 
 ```js
-var x = require('xastscript');
+import x from 'xastscript';
 console.log(x("album", {
   id: 123
 }, x("name", null, "Born in the U.S.A."), x("artist", null, "Bruce Springsteen"), x("releasedate", {
@@ -82,6 +88,9 @@ console.log(x(null, null, 1 + 1, x("self-closing"), x("x", Object.assign({
 
 ## API
 
+This package exports the following identifiers: `buildJsx`.
+There is no default export.
+
 ### `buildJsx(tree, options?)`
 
 Turn JSX in `tree` ([`Program`][program]) into hyperscript calls.
@@ -125,15 +134,17 @@ This is done automatically by [`espree`][espree].
 For [`acorn`][acorn], it can be done like so:
 
 ```js
-var acorn = require('acorn')
-var jsx = require('acorn-jsx')
+import {Parser} from 'acorn'
+import jsx from 'acorn-jsx'
+
+var doc = ''
 
 var comments = []
-var tree = acorn.Parser.extend(jsx()).parse(doc, {onComment: comments})
+var tree = Parser.extend(jsx()).parse(doc, {onComment: comments})
 tree.comments = comments
 ```
 
-In almost all cases, this utility is the same as the babel plugin, except that
+In almost all cases, this utility is the same as the Babel plugin, except that
 they work on slightly different syntax trees.
 
 Some differences: