Convert to ES Modules

.github/workflows/ci.yml

@@ -17,5 +17,8 @@ jobs:
       - uses: actions/setup-node@v1
         with:
           node-version: ${{ matrix.node-version }}
-      - run: npm install
-      - run: npm test
+      - uses: pnpm/[email protected]
+        with:
+            run_install: true
+      - run: pnpm build
+      - run: pnpm test

.gitignore

@@ -4,3 +4,4 @@ package-lock.json
 yarn.lock
 npm-debug.log
 yarn-error.log
+dist/

README.md

@@ -10,7 +10,7 @@ npm install arg
 
 ## Usage
 
-`arg()` takes either 1 or 2 arguments:
+`arg.run()` takes either 1 or 2 arguments:
 
 1. Command line specification object (see below)
 2. Parse options (_Optional_, defaults to `{permissive: false, argv: process.argv.slice(2), stopAtPositional: false}`)
@@ -27,10 +27,19 @@ in which case an empty array is returned).
 const arg = require('arg');
 
 // `options` is an optional parameter
-const args = arg(
+const args = arg.run(
 	spec,
 	(options = { permissive: false, argv: process.argv.slice(2) })
 );
+
+// It also supports ESM
+import * as arg from 'arg'
+
+const args = arg.run(
+	spec,
+	(options = { permissive: false, argv: process.argv.slice(2) })
+);
+
 ```
 
 For example:
@@ -43,7 +52,7 @@ $ node ./hello.js --verbose -vvv --port=1234 -n 'My name' foo bar --tag qux --ta
 // hello.js
 const arg = require('arg');
 
-const args = arg({
+const args = arg.run({
 	// Types
 	'--help': Boolean,
 	'--version': Boolean,
@@ -116,7 +125,7 @@ function myHandler(value, argName, previousValue) {
 	return 'na ' + (previousValue || 'batman!');
 }
 
-const args = arg(
+const args = arg.run(
 	{
 		'--foo': arg.flag(myHandler),
 		'-f': '--foo'
@@ -144,7 +153,7 @@ const arg = require('arg');
 
 const argv = ['-AAAA', '-BBBB'];
 
-const args = arg(
+const args = arg.run(
 	{
 		'-A': arg.COUNT,
 		'-B': [Boolean]
@@ -166,7 +175,7 @@ console.log(args);
 
 ### Options
 
-If a second parameter is specified and is an object, it specifies parsing options to modify the behavior of `arg()`.
+If a second parameter is specified and is an object, it specifies parsing options to modify the behavior of `arg.run()`.
 
 #### `argv`
 
@@ -176,7 +185,7 @@ slice them from `process.argv`) you may specify them in the `argv` option.
 For example:
 
 ```javascript
-const args = arg(
+const args = arg.run(
 	{
 		'--foo': String
 	},
@@ -216,7 +225,7 @@ const argv = [
 	'hello again'
 ];
 
-const args = arg(
+const args = arg.run(
 	{
 		'--foo': String,
 		'--bar': Number
@@ -250,7 +259,7 @@ const arg = require('arg');
 
 const argv = ['--foo', 'hello', '--bar'];
 
-const args = arg(
+const args = arg.run(
 	{
 		'--foo': Boolean,
 		'--bar': Boolean
@@ -283,7 +292,7 @@ If an unknown option (not defined in the spec object) is passed, an error with c
 ```js
 // cli.js
 try {
-	require('arg')({ '--hi': String });
+	require('arg').run({ '--hi': String });
 } catch (err) {
 	if (err.code === 'ARG_UNKNOWN_OPTION') {
 		console.log(err.message);
@@ -307,7 +316,7 @@ A few questions and answers that have been asked before:
 Do the assertion yourself, such as:
 
 ```javascript
-const args = arg({ '--name': String });
+const args = arg.run({ '--name': String });
 
 if (!args['--name']) throw new Error('missing required argument: --name');
 ```

index.d.ts

@@ -1,44 +1,39 @@
-declare function arg<T extends arg.Spec>(
-	spec: T,
-	options?: arg.Options
-): arg.Result<T>;
-
-declare namespace arg {
-	export const flagSymbol: unique symbol;
-
-	export function flag<T>(fn: T): T & { [arg.flagSymbol]: true };
-
-	export const COUNT: Handler<number> & { [arg.flagSymbol]: true };
-
-	export type Handler<T = any> = (
-		value: string,
-		name: string,
-		previousValue?: T
-	) => T;
-
-	export class ArgError extends Error {
-		constructor(message: string, code: string);
-
-		code: string;
-	}
-
-	export interface Spec {
-		[key: string]: string | Handler | [Handler];
-	}
-
-	export type Result<T extends Spec> = { _: string[] } & {
-		[K in keyof T]?: T[K] extends Handler
-			? ReturnType<T[K]>
-			: T[K] extends [Handler]
-			? Array<ReturnType<T[K][0]>>
-			: never;
-	};
-
-	export interface Options {
-		argv?: string[];
-		permissive?: boolean;
-		stopAtPositional?: boolean;
-	}
+// Types
+export type Handler<T = any> = (
+	value: string,
+	name: string,
+	previousValue?: T
+) => T;
+
+export interface Spec {
+	[key: string]: string | Handler | [Handler];
 }
 
-export = arg;
+export type Result<T extends Spec> = { _: string[] } & {
+	[K in keyof T]?: T[K] extends Handler
+		? ReturnType<T[K]>
+		: T[K] extends [Handler]
+		? Array<ReturnType<T[K][0]>>
+		: never;
+};
+
+export interface Options {
+	argv?: string[];
+	permissive?: boolean;
+	stopAtPositional?: boolean;
+}
+
+// Exports
+declare const flagSymbol: unique symbol;
+
+export class ArgError extends Error {
+	constructor(message: string, code: string);
+
+	code: string;
+}
+
+export function run<T extends Spec>(spec: T, options?: Options): Result<T>;
+
+export function flag<T>(fn: T): T & { [flagSymbol]: true };
+
+export const COUNT: Handler<number> & { [flagSymbol]: true };

index.js

@@ -1,6 +1,6 @@
 const flagSymbol = Symbol('arg flag');
 
-class ArgError extends Error {
+export class ArgError extends Error {
 	constructor(msg, code) {
 		super(msg);
 		this.name = 'ArgError';
@@ -10,7 +10,7 @@ class ArgError extends Error {
 	}
 }
 
-function arg(
+export function run(
 	opts,
 	{
 		argv = process.argv.slice(2),
@@ -181,15 +181,10 @@ function arg(
 	return result;
 }
 
-arg.flag = (fn) => {
+export function flag(fn) {
 	fn[flagSymbol] = true;
 	return fn;
-};
+}
 
 // Utility types
-arg.COUNT = arg.flag((v, name, existingCount) => (existingCount || 0) + 1);
-
-// Expose error class
-arg.ArgError = ArgError;
-
-module.exports = arg;
+export const COUNT = flag((v, name, existingCount) => (existingCount || 0) + 1);

package.json

@@ -2,22 +2,35 @@
   "name": "arg",
   "version": "5.0.2",
   "description": "Unopinionated, no-frills CLI argument parser",
-  "main": "index.js",
-  "types": "index.d.ts",
   "repository": "vercel/arg",
   "author": "Josh Junon <[email protected]>",
   "license": "MIT",
   "files": [
-    "index.js",
+    "dist",
     "index.d.ts"
   ],
+  "main": "./dist/index.js",
+  "module": "./dist/index.mjs",
+  "types": "./index.d.ts",
+  "exports": {
+    ".": {
+      "require": "./dist/index.js",
+      "import": "./dist/index.mjs",
+      "types": "./index.d.ts"
+    }
+  },
+  "packageManager": "[email protected]",
   "scripts": {
+    "build": "tsup index.js --format cjs,esm --clean",
+    "prepublishOnly": "pnpm build",
+    "format": "prettier -w .",
     "test": "WARN_EXIT=1 jest --coverage -w 2"
   },
   "devDependencies": {
-    "chai": "^4.1.1",
-    "jest": "^27.0.6",
-    "prettier": "^2.3.2"
+    "chai": "^4.3.6",
+    "jest": "^29.2.0",
+    "prettier": "^2.7.1",
+    "tsup": "^6.2.3"
   },
   "prettier": {
     "arrowParens": "always",