BREAKING: Provides dual ESM/CJS exports

This change makes lib/get-transformer.js unavailable for import

.eslintrc.yml

@@ -16,4 +16,7 @@ rules:
   import/first: error
   import/no-anonymous-default-export: error
   import/no-unassigned-import: error
-  import/no-internal-modules: error
+  import/no-internal-modules:
+    - error
+    - allow:
+        - src/**

.gitignore

@@ -5,4 +5,6 @@ npm-debug.log*
 coverage
 coverage.info
 test/fixtures/*/build
-node_modules
+node_modules
+lib
+!lib/*.d.ts

.prettierignore

@@ -1,3 +1,4 @@
 test/fixtures/**
 coverage/**
-package-lock.json
+package-lock.json
+lib

package.json

@@ -1,4 +1,5 @@
 {
+  "name": "@metalsmith/in-place",
   "author": "ismay",
   "description": "A metalsmith plugin for in-place templating",
   "license": "MIT",
@@ -8,8 +9,14 @@
     "metalsmith-plugin",
     "metalsmith"
   ],
-  "main": "lib/index.js",
-  "name": "@metalsmith/in-place",
+  "source": "src/index.js",
+  "main": "lib/index.cjs",
+  "module": "lib/index.js",
+  "type": "module",
+  "exports": {
+    "import": "./lib/index.js",
+    "require": "./lib/index.cjs"
+  },
   "repository": {
     "type": "git",
     "url": "https://github.com/metalsmith/in-place.git"
@@ -26,6 +33,8 @@
     "format:check": "prettier --list-different \"**/*.{yml,md,js,json}\"",
     "test": "c8 mocha",
     "release": "release-it",
+    "build": "microbundle --target node -f cjs,esm --strict --generateTypes=false",
+    "prepack": "npm run build",
     "lint": "eslint --fix .",
     "lint:check": "eslint --fix-dry-run ."
   },
@@ -42,6 +51,7 @@
     "jstransformer-marked": "^1.2.0",
     "jstransformer-pug": "^0.4.0",
     "metalsmith": "^2.6.0",
+    "microbundle": "^0.15.1",
     "mocha": "^10.2.0",
     "nyc": "^15.1.0",
     "prettier": "^2.8.8",

lib/get-transformer.js → src/get-transformer.js

@@ -1,5 +1,5 @@
-const jstransformer = require('jstransformer')
-const toTransformer = require('inputformat-to-jstransformer')
+import jstransformer from 'jstransformer'
+import toTransformer from 'inputformat-to-jstransformer'
 
 /**
  * Gets jstransformer for an extension, and caches them
@@ -18,4 +18,4 @@ function getTransformer(ext) {
   return cache[ext]
 }
 
-module.exports = getTransformer
+export default getTransformer

lib/index.js → src/index.js

@@ -1,6 +1,7 @@
-const path = require('path')
-const isUtf8 = require('is-utf8')
-const getTransformer = require('./get-transformer')
+import path from 'node:path'
+import isUtf8 from 'is-utf8'
+import getTransformer from './get-transformer.js'
+
 let debug = () => {
   throw new Error('uninstantiated debug')
 }
@@ -164,4 +165,4 @@ function initializeInPlace(options = defaultOptions) {
   }
 }
 
-module.exports = initializeInPlace
+export default initializeInPlace

test/index.js

@@ -1,11 +1,15 @@
 /* eslint-env node, mocha */
 
-const { strictEqual, deepStrictEqual } = require('assert')
-const Metalsmith = require('metalsmith')
-const equal = require('assert-dir-equal')
-const { name } = require('../package.json')
-const { resolve } = require('path')
-const plugin = require('../lib')
+import { strictEqual, deepStrictEqual } from 'node:assert'
+import { resolve, dirname } from 'node:path'
+import { fileURLToPath } from 'node:url'
+import { readFileSync } from 'node:fs'
+import Metalsmith from 'metalsmith'
+import equal from 'assert-dir-equal'
+import plugin from '../src/index.js'
+
+const __dirname = dirname(fileURLToPath(import.meta.url))
+const { name } = JSON.parse(readFileSync(resolve(__dirname, '../package.json'), 'utf-8'))
 
 function fixture(p) {
   return resolve(__dirname, 'fixtures', p)