Add TypeScript definition (#116)

index.d.ts

@@ -0,0 +1,198 @@
+import {PackageJson} from 'type-fest';
+import {Options as MinimistOptions} from 'minimist-options';
+
+export interface Options {
+	/**
+	Define argument flags.
+
+	The key is the flag name and the value is an object with any of:
+
+	- `type`: Type of value. (Possible values: `string` `boolean`)
+	- `alias`: Usually used to define a short flag alias.
+	- `default`: Default value when the flag is not specified.
+
+	@example
+	```
+	flags: {
+		unicorn: {
+			type: 'string',
+			alias: 'u',
+			default: 'rainbow'
+		}
+	}
+	```
+	*/
+	readonly flags?: MinimistOptions;
+
+	/**
+	Description to show above the help text. Default: The package.json `"description"` property.
+
+	Set it to `false` to disable it altogether.
+	*/
+	readonly description?: string | false;
+
+	/**
+	The help text you want shown.
+
+	The input is reindented and starting/ending newlines are trimmed which means you can use a [template literal](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/template_strings) without having to care about using the correct amount of indent.
+
+	The description will be shown above your help text automatically.
+
+	Set it to `false` to disable it altogether.
+	*/
+	readonly help?: string | false;
+
+	/**
+	Set a custom version output. Default: The package.json `"version"` property.
+
+	Set it to `false` to disable it altogether.
+	*/
+	readonly version?: string | false;
+
+	/**
+	Automatically show the help text when the `--help` flag is present. Useful to set this value to `false` when a CLI manages child CLIs with their own help text.
+	*/
+	readonly autoHelp?: boolean;
+
+	/**
+	Automatically show the version text when the `--version` flag is present. Useful to set this value to `false` when a CLI manages child CLIs with their own version text.
+	*/
+	readonly autoVersion?: boolean;
+
+	/**
+	package.json as an `Object`. Default: Closest package.json upwards.
+
+	_You most likely don't need this option._
+	*/
+	readonly pkg?: {[key: string]: unknown};
+
+	/**
+	Custom arguments object.
+
+	@default process.argv.slice(2)
+	*/
+	readonly argv?: ReadonlyArray<string>;
+
+	/**
+	Infer the argument type.
+
+	By default, the argument `5` in `$ foo 5` becomes a string. Enabling this would infer it as a number.
+
+	@default false
+	*/
+	readonly inferType?: boolean;
+
+	/**
+	Value of `boolean` flags not defined in `argv`. If set to `undefined` the flags not defined in `argv` will be excluded from the result. The `default` value set in `boolean` flags take precedence over `booleanDefault`.
+
+	__Caution: Explicitly specifying undefined for `booleanDefault` has different meaning from omitting key itself.__
+
+	@example
+	```
+	const cli = meow(`
+		Usage
+			$ foo
+
+		Options
+			--rainbow, -r  Include a rainbow
+			--unicorn, -u  Include a unicorn
+			--no-sparkles  Exclude sparkles
+
+		Examples
+			$ foo
+			🌈 unicorns✨🌈
+	`, {
+		booleanDefault: undefined,
+		flags: {
+			rainbow: {
+				type: 'boolean',
+				default: true,
+				alias: 'r'
+			},
+				unicorn: {
+				type: 'boolean',
+				default: false,
+				alias: 'u'
+			},
+			cake: {
+				type: 'boolean',
+				alias: 'c'
+			},
+			sparkles: {
+				type: 'boolean',
+				default: true
+			}
+		}
+	});
+
+	//{
+	//	flags: {
+	//		rainbow: true,
+	//		unicorn: false,
+	//		sparkles: true
+	//	},
+	//	unnormalizedFlags: {
+	//		rainbow: true,
+	//		r: true,
+	//		unicorn: false,
+	//		u: false,
+	//		sparkles: true
+	//	},
+	//	…
+	//}
+	 ```
+	*/
+	readonly booleanDefault?: boolean | null | undefined;
+
+	/**
+	Whether to use [hard-rejection](https://github.com/sindresorhus/hard-rejection) or not. Disabling this can be useful if you need to handle `process.on('unhandledRejection')` yourself.
+
+	@default true
+	*/
+	readonly hardRejection?: boolean;
+}
+
+export interface Result {
+	/**
+	Non-flag arguments.
+	*/
+	input: string[];
+
+	/**
+	Flags converted to camelCase excluding aliases.
+	*/
+	flags: {[name: string]: unknown};
+
+	/**
+	Flags converted camelCase including aliases.
+	*/
+	unnormalizedFlags: {[name: string]: unknown};
+
+	/**
+	The `package.json` object.
+	*/
+	pkg: PackageJson;
+
+	/**
+	The help text used with `--help`.
+	*/
+	help: string;
+
+	/**
+	Show the help text and exit with code.
+
+	@param exitCode - The exit code to use. Default: `2`.
+	*/
+	showHelp(exitCode?: number): void;
+
+	/**
+	Show the version text and exit.
+	*/
+	showVersion(): void;
+}
+
+/**
+@param helpMessage - Shortcut for the `help` option.
+*/
+export default function meow(helpMessage: string, options?: Options): Result;
+export default function meow(options?: Options): Result;

index.js

@@ -14,7 +14,7 @@ const normalizePackageData = require('normalize-package-data');
 delete require.cache[__filename];
 const parentDir = path.dirname(module.parent.filename);
 
-module.exports = (helpText, options) => {
+const meow = (helpText, options) => {
 	if (typeof helpText !== 'string') {
 		options = helpText;
 		helpText = '';
@@ -126,3 +126,6 @@ module.exports = (helpText, options) => {
 		showVersion
 	};
 };
+
+module.exports = meow;
+module.exports.default = meow;

index.test-d.ts

@@ -0,0 +1,47 @@
+import {expectType} from 'tsd-check';
+import {PackageJson} from 'type-fest';
+import meow, {Result} from '.';
+
+expectType<Result>(meow('Help text'));
+expectType<Result>(meow('Help text', {hardRejection: false}));
+expectType<Result>(
+	meow({
+		flags: {
+			unicorn: {
+				type: 'boolean',
+				alias: 'u'
+			},
+			fooBar: {
+				type: 'string',
+				default: 'foo'
+			}
+		}
+	})
+);
+expectType<Result>(meow({description: 'foo'}));
+expectType<Result>(meow({description: false}));
+expectType<Result>(meow({help: 'foo'}));
+expectType<Result>(meow({help: false}));
+expectType<Result>(meow({version: 'foo'}));
+expectType<Result>(meow({version: false}));
+expectType<Result>(meow({autoHelp: false}));
+expectType<Result>(meow({autoVersion: false}));
+expectType<Result>(meow({pkg: {foo: 'bar'}}));
+expectType<Result>(meow({argv: ['foo', 'bar']}));
+expectType<Result>(meow({inferType: true}));
+expectType<Result>(meow({booleanDefault: true}));
+expectType<Result>(meow({booleanDefault: null}));
+expectType<Result>(meow({booleanDefault: undefined}));
+expectType<Result>(meow({hardRejection: false}));
+
+const result = meow('Help text');
+
+expectType<string[]>(result.input);
+expectType<{[name: string]: unknown}>(result.flags);
+expectType<{[name: string]: unknown}>(result.unnormalizedFlags);
+expectType<PackageJson>(result.pkg);
+expectType<string>(result.help);
+
+result.showHelp();
+result.showHelp(1);
+result.showVersion();

package.json

@@ -13,10 +13,11 @@
 		"node": ">=8"
 	},
 	"scripts": {
-		"test": "xo && ava"
+		"test": "xo && ava && tsd-check"
 	},
 	"files": [
-		"index.js"
+		"index.js",
+		"index.d.ts"
 	],
 	"keywords": [
 		"cli",
@@ -38,21 +39,24 @@
 		"console"
 	],
 	"dependencies": {
+		"@types/minimist": "^1.2.0",
 		"camelcase-keys": "^5.0.0",
-		"decamelize-keys": "^1.0.0",
+		"decamelize-keys": "^1.1.0",
 		"hard-rejection": "^1.0.0",
-		"minimist-options": "^3.0.1",
-		"normalize-package-data": "^2.3.4",
+		"minimist-options": "^4.0.1",
+		"normalize-package-data": "^2.5.0",
 		"read-pkg-up": "^4.0.0",
 		"redent": "^2.0.0",
 		"trim-newlines": "^2.0.0",
+		"type-fest": "^0.2.0",
 		"yargs-parser": "^11.0.0"
 	},
 	"devDependencies": {
-		"ava": "^0.25.0",
+		"ava": "^1.3.1",
 		"execa": "^1.0.0",
-		"indent-string": "^3.0.0",
-		"xo": "^0.23.0"
+		"indent-string": "^3.2.0",
+		"tsd-check": "^0.3.0",
+		"xo": "^0.24.0"
 	},
 	"xo": {
 		"rules": {

readme.md

@@ -77,7 +77,7 @@ Returns an `Object` with:
 - `unnormalizedFlags` *(Object)* - Flags converted camelCase including aliases
 - `pkg` *(Object)* - The `package.json` object
 - `help` *(string)* - The help text used with `--help`
-- `showHelp([code=2])` *(Function)* - Show the help text and exit with `code`
+- `showHelp([exitCode=2])` *(Function)* - Show the help text and exit with `exitCode`
 - `showVersion()` *(Function)* - Show the version text and exit
 
 #### helpText