Add support for --import with register()

.github/workflows/npm-publish.yml

@@ -15,7 +15,7 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3
         with:
-          node-version: 19
+          node-version: 20.6
       - run: npm ci
       - run: npm test
 
@@ -26,7 +26,7 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3
         with:
-          node-version: 19
+          node-version: 20.6
           registry-url: https://registry.npmjs.org/
       - run: npm ci
       - run: npm publish

README.md

@@ -10,12 +10,18 @@ npm i extensionless
 
  
 
-Start `node` with the following flag added:
+Start `node` with one of the following flags added. If you're running on a version of node older than `20.6.0`, use:
 
 ```
 --experimental-loader=extensionless
 ```
 
+or else, use the newer one instead:
+
+```
+--import=extensionless/register
+```
+
  
 
 You can now use import specifiers as file paths without extensions or as directory paths:

package.json

@@ -1,8 +1,11 @@
 {
   "name": "extensionless",
-  "version": "1.4.5",
+  "version": "1.5.6",
   "type": "module",
-  "main": "src/index.js",
+  "exports": {
+    ".": "./src/index.js",
+    "./register": "./src/register.js"
+  },
   "license": "MIT",
   "description": "Node.js loader for import specifiers as file paths without extensions or as directory paths",
   "keywords": [
@@ -17,6 +20,6 @@
     "url": "git+https://github.com/barhun/extensionless.git"
   },
   "scripts": {
-    "test": "node --experimental-loader=./src/index.js test"
+    "test": "node --import=./src/register.js test"
   }
 }

src/config.js

@@ -1,33 +1,37 @@
 import {readFile} from 'fs/promises'
 import {dirname, isAbsolute, join} from 'path'
-import {argv, cwd} from 'process'
+import {cwd} from 'process'
 
-let pkgJson = await (async () => {
-  let curDir, upDir = isAbsolute(argv[1] ?? '') ? argv[1] : cwd()
+let warn = (field, desc) => console.warn('⚠️ \x1b[33m%s\x1b[0m',
+  `Warning: The package.json field 'extensionless.${field}' must be ${desc}! Using the default value instead...`
+)
+
+let getPkgJson = async argv1 => {
+  let path = isAbsolute(argv1 ?? '') ? argv1 : cwd()
 
   do {
     try {
-      return JSON.parse(await readFile(join(curDir = upDir, 'package.json'), 'utf8'))
+      return JSON.parse(await readFile(join(path, 'package.json'), 'utf8'))
     } catch (e) {
       if (!['ENOTDIR', 'ENOENT', 'EISDIR'].includes(e.code)) {
         throw new Error('Cannot retrieve package.json', {cause: e})
       }
     }
-  } while (curDir !== (upDir = dirname(curDir)))
-})()
-
-let warn = (field, desc) => console.warn('⚠️ \x1b[33m%s\x1b[0m', `Warning: The package.json field 'extensionless.${field}' must be ${desc}! Using the default value instead...`)
+  } while (path !== (path = dirname(path)))
+}
 
-let defaults = {
-  lookFor: ['js']
-}, {
-  lookFor
-} = {...defaults, ...pkgJson?.extensionless}
+export async function getConfig({argv1} = {}) {
+  let defaults = {
+    lookFor: ['js']
+  }, {
+    lookFor
+  } = {...defaults, ...(await getPkgJson(argv1))?.extensionless}
 
-Array.isArray(lookFor) && lookFor.length && lookFor.every(a => typeof a === 'string' && /^[a-z]+\w*$/i.test(a)) || (
-  lookFor = defaults.lookFor, warn('lookFor', 'an array of alphanumeric strings')
-)
+  Array.isArray(lookFor) && lookFor.length && lookFor.every(a => typeof a === 'string' && /^[a-z]+\w*$/i.test(a)) || (
+    lookFor = defaults.lookFor, warn('lookFor', 'an array of alphanumeric strings')
+  )
 
-export {
-  lookFor
+  return {
+    lookFor
+  }
 }

src/index.js

@@ -1,8 +1,20 @@
 import {extname, isAbsolute} from 'path'
-import {lookFor} from './config.js'
+import {getConfig} from './config.js'
 
-let indexFiles = [lookFor.map(e => `index.${e}`), ['index.json']]
-let candidates = indexFiles.map(i => i.map(f => extname(f)).concat(i.map(f => `/${f}`)))
+let initPromise
+export function globalPreload({port}) {
+  port.onmessage = e => initPromise = initialize({argv1: e.data})
+
+  return 'port.postMessage(process.argv[1])'
+}
+
+let indexFiles, candidates
+export async function initialize(data) {
+  let {lookFor} = await getConfig(data)
+
+  indexFiles = [lookFor.map(e => `index.${e}`), ['index.json']]
+  candidates = indexFiles.map(i => i.map(f => extname(f)).concat(i.map(f => `/${f}`)))
+}
 
 let relSpecs = ['.', '..'], prefixes = ['./', '../', 'file://', '.\\', '..\\']
 let extToSkip = ['.js', '.cjs', '.mjs', '.json', '.node', '.wasm'], empty = [[], []]
@@ -14,6 +26,7 @@ export async function resolve(specifier, {importAssertions, parentURL}, nextReso
     return await nextResolve(specifier)
   }
 
+  await initPromise
   let selfURL = new URL((isAbs ? 'file://' : '') + specifier, parentURL).href
   let postfixes = selfURL.endsWith('/') ? indexFiles : extToSkip.includes(extname(selfURL)) ? empty : candidates
 

src/register.js

@@ -0,0 +1,4 @@
+import {register} from 'module'
+import {argv} from 'process'
+
+register('./index.js', import.meta.url, {data: {argv1: argv[1]}})