feat: support loading esm and ts files from json config

src/index.js

@@ -1,13 +1,12 @@
+// @ts-check
 const { resolve } = require('node:path')
-const { pathToFileURL } = require('node:url')
 
 const config = require('lilconfig')
 const yaml = require('yaml')
 
 const loadOptions = require('./options.js')
 const loadPlugins = require('./plugins.js')
-
-const TS_EXT_RE = /\.(c|m)?ts$/
+const req = require('./req.js')
 
 const interopRequireDefault = obj =>
   obj && obj.__esModule ? obj : { default: obj }
@@ -18,9 +17,9 @@ const interopRequireDefault = obj =>
  * @param  {Object} ctx Config Context
  * @param  {Object} result Cosmiconfig result
  *
- * @return {Object} PostCSS Config
+ * @return {Promise<Object>} PostCSS Config
  */
-function processResult(ctx, result) {
+async function processResult(ctx, result) {
   let file = result.filepath || ''
   let projectConfig = interopRequireDefault(result.config).default || {}
 
@@ -36,8 +35,8 @@ function processResult(ctx, result) {
 
   let res = {
     file,
-    options: loadOptions(projectConfig, file),
-    plugins: loadPlugins(projectConfig, file)
+    options: await loadOptions(projectConfig, file),
+    plugins: await loadPlugins(projectConfig, file)
   }
   delete projectConfig.plugins
   return res
@@ -72,38 +71,8 @@ function createContext(ctx) {
   return ctx
 }
 
-/** @type {import('jiti').JITI | null} */
-let jiti = null
-
 async function loader(filepath) {
-  try {
-    let module = await import(pathToFileURL(filepath).href)
-    return module.default
-  } catch (err) {
-    /* c8 ignore start */
-    if (!TS_EXT_RE.test(filepath)) {
-      throw err
-    }
-    if (!jiti) {
-      try {
-        jiti = (await import('jiti')).default(__filename, {
-          interopDefault: true
-        })
-      } catch (jitiErr) {
-        if (
-          jitiErr.code === 'ERR_MODULE_NOT_FOUND' &&
-          jitiErr.message.includes("Cannot find package 'jiti'")
-        ) {
-          throw new Error(
-            `'jiti' is required for the TypeScript configuration files. Make sure it is installed\nError: ${jitiErr.message}`
-          )
-        }
-        throw jitiErr
-      }
-      /* c8 ignore stop */
-    }
-    return jiti(filepath)
-  }
+  return req(filepath)
 }
 
 const withLoaders = (options = {}) => {

src/options.js

@@ -1,3 +1,4 @@
+// @ts-check
 const req = require('./req.js')
 
 /**
@@ -8,12 +9,12 @@ const req = require('./req.js')
  *
  * @param  {Object} config  PostCSS Config
  *
- * @return {Object} options PostCSS Options
+ * @return {Promise<Object>} options PostCSS Options
  */
-function options(config, file) {
+async function options(config, file) {
   if (config.parser && typeof config.parser === 'string') {
     try {
-      config.parser = req(config.parser, file)
+      config.parser = await req(config.parser, file)
     } catch (err) {
       throw new Error(
         `Loading PostCSS Parser failed: ${err.message}\n\n(@${file})`
@@ -23,7 +24,7 @@ function options(config, file) {
 
   if (config.syntax && typeof config.syntax === 'string') {
     try {
-      config.syntax = req(config.syntax, file)
+      config.syntax = await req(config.syntax, file)
     } catch (err) {
       throw new Error(
         `Loading PostCSS Syntax failed: ${err.message}\n\n(@${file})`
@@ -33,7 +34,7 @@ function options(config, file) {
 
   if (config.stringifier && typeof config.stringifier === 'string') {
     try {
-      config.stringifier = req(config.stringifier, file)
+      config.stringifier = await req(config.stringifier, file)
     } catch (err) {
       throw new Error(
         `Loading PostCSS Stringifier failed: ${err.message}\n\n(@${file})`

src/plugins.js

@@ -1,3 +1,4 @@
+// @ts-check
 const req = require('./req.js')
 
 /**
@@ -9,18 +10,19 @@ const req = require('./req.js')
  * @param  {String} plugin PostCSS Plugin Name
  * @param  {Object} options PostCSS Plugin Options
  *
- * @return {Function} PostCSS Plugin
+ * @return {Promise<Function>} PostCSS Plugin
  */
-function load(plugin, options, file) {
+async function load(plugin, options, file) {
   try {
     if (
       options === null ||
       options === undefined ||
       Object.keys(options).length === 0
     ) {
-      return req(plugin, file)
+      return await req(plugin, file)
     } else {
-      return req(plugin, file)(options)
+      return (await req(plugin, file))(options)
+      /* c8 ignore next */
     }
   } catch (err) {
     throw new Error(
@@ -37,21 +39,22 @@ function load(plugin, options, file) {
  *
  * @param {Object} config PostCSS Config Plugins
  *
- * @return {Array} plugins PostCSS Plugins
+ * @return {Promise<Array>} plugins PostCSS Plugins
  */
-function plugins(config, file) {
+async function plugins(config, file) {
   let list = []
 
   if (Array.isArray(config.plugins)) {
     list = config.plugins.filter(Boolean)
   } else {
-    list = Object.keys(config.plugins)
-      .filter(plugin => {
-        return config.plugins[plugin] !== false ? plugin : ''
+    list = Object.entries(config.plugins)
+      .filter(([plugin, options]) => {
+        return options !== false ? plugin : false
       })
-      .map(plugin => {
-        return load(plugin, config.plugins[plugin], file)
+      .map(([plugin, options]) => {
+        return load(plugin, options, file)
       })
+    list = await Promise.all(list)
   }
 
   if (list.length && list.length > 0) {

src/req.js

@@ -1,10 +1,39 @@
-// eslint-disable-next-line n/no-deprecated-api
-const { createRequire, createRequireFromPath } = require('node:module')
+// @ts-check
+const { createRequire } = require('node:module')
 
-function req (name, rootFile) {
-  let create = createRequire || createRequireFromPath
-  let require = create(rootFile)
-  return require(name)
+const TS_EXT_RE = /\.(c|m)?ts$/
+
+/** @type {import('jiti').default | null} */
+let jiti = null
+
+/**
+ * @param {string} name
+ * @param {string} rootFile
+ * @returns {Promise<any>}
+ */
+async function req(name, rootFile = __filename) {
+  let __require = createRequire(rootFile)
+  let url = __require.resolve(name)
+
+  try {
+    return (await import(url)).default
+  } catch (err) {
+    if (!TS_EXT_RE.test(url)) {
+      /* c8 ignore start */
+      throw err
+    }
+    if (!jiti) {
+      try {
+        jiti = (await import('jiti')).default
+      } catch (jitiErr) {
+        throw new Error(
+          `'jiti' is required for the TypeScript configuration files. Make sure it is installed\nError: ${jitiErr.message}`
+        )
+      }
+      /* c8 ignore stop */
+    }
+    return jiti(rootFile, { interopDefault: true })(name)
+  }
 }
 
 module.exports = req

test/ts.test.js

@@ -150,3 +150,20 @@ describe('Array', () => {
     equal(config.file, resolve(expectedPath))
   }
 })
+
+describe('JSON', () => {
+  test('Load Config - postcss.config.mts', async () => {
+    let { plugins } = await postcssrc(ctx, 'test/ts/json')
+    equal(plugins.length, 6)
+    plugins.forEach((plugin, index) => {
+      equal(
+        // normalize for simplicity
+        plugin.path
+          .replace(/^.*?:\/\//, '')
+          .replace(/\\/g, '/')
+          .replace(/\.[^.]+$/, ''),
+        resolve(process.cwd(), `test/ts/json/postcss/${index + 1}`)
+      )
+    })
+  })
+})

test/ts/json/.postcssrc.json

@@ -0,0 +1,10 @@
+{
+  "plugins": {
+    "./postcss/1.js": {},
+    "./postcss/2.cjs": {},
+    "./postcss/3.mjs": {},
+    "./postcss/4.ts": {},
+    "./postcss/5.cts": {},
+    "./postcss/6.mts": {}
+  }
+}

test/ts/json/postcss/1.js

@@ -0,0 +1,8 @@
+module.exports = function plugin() {
+  return {
+    postcssPlugin: '1'
+  }
+}
+
+module.exports.postcss = true
+module.exports.path = __filename

test/ts/json/postcss/2.cjs

@@ -0,0 +1,8 @@
+module.exports = function plugin() {
+  return {
+    postcssPlugin: '2'
+  }
+}
+
+module.exports.postcss = true
+module.exports.path = __filename

test/ts/json/postcss/3.mjs

@@ -0,0 +1,9 @@
+let plugin = () => {
+  return {
+    postcssPlugin: '3'
+  }
+}
+plugin.postcss = true
+plugin.path = import.meta.url
+
+export default plugin

test/ts/json/postcss/4.ts

@@ -0,0 +1,9 @@
+let plugin: any = () => {
+  return {
+    postcssPlugin: '4'
+  }
+}
+plugin.postcss = true
+plugin.path = __filename
+
+export = plugin

test/ts/json/postcss/5.cts

@@ -0,0 +1,9 @@
+let plugin: any = () => {
+  return {
+    postcssPlugin: '5'
+  }
+}
+plugin.postcss = true
+plugin.path = __filename
+
+export = plugin

test/ts/json/postcss/6.mts

@@ -0,0 +1,10 @@
+let plugin: any = () => {
+  return {
+    postcssPlugin: '6'
+  }
+}
+plugin.postcss = true
+// @ts-ignore
+plugin.path = import.meta.url
+
+export default plugin