From 6dd27c4b6a3ebaa42ddbf4e93c20e2b4d90bad07 Mon Sep 17 00:00:00 2001
From: Jordan Harband <ljharb@gmail.com>
Date: Wed, 1 Jan 2025 23:15:31 -0800
Subject: [PATCH] [New] add types

---
 index.d.ts       | 3 +++
 index.js         | 7 ++++++-
 package.json     | 7 +++++++
 test/corejs.js   | 1 +
 test/index.js    | 1 +
 test/uglified.js | 1 +
 tsconfig.json    | 9 +++++++++
 7 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 index.d.ts
 create mode 100644 tsconfig.json

diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..38eec07
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,3 @@
+declare function isGeneratorFunction(fn: unknown): fn is GeneratorFunction;
+
+export = isGeneratorFunction;
\ No newline at end of file
diff --git a/index.js b/index.js
index 3d340ee..01abeae 100644
--- a/index.js
+++ b/index.js
@@ -18,8 +18,10 @@ var getGeneratorFunc = function () { // eslint-disable-line consistent-return
 	} catch (e) {
 	}
 };
+/** @type {undefined | false | null | GeneratorFunctionConstructor} */
 var GeneratorFunction;
 
+/** @type {import('.')} */
 module.exports = function isGeneratorFunction(fn) {
 	if (typeof fn !== 'function') {
 		return false;
@@ -36,7 +38,10 @@ module.exports = function isGeneratorFunction(fn) {
 	}
 	if (typeof GeneratorFunction === 'undefined') {
 		var generatorFunc = getGeneratorFunc();
-		GeneratorFunction = generatorFunc ? getProto(generatorFunc) : false;
+		GeneratorFunction = generatorFunc
+			// eslint-disable-next-line no-extra-parens
+			? /** @type {GeneratorFunctionConstructor} */ (getProto(generatorFunc))
+			: false;
 	}
 	return getProto(fn) === GeneratorFunction;
 };
diff --git a/package.json b/package.json
index 432bbc3..a7cbad2 100644
--- a/package.json
+++ b/package.json
@@ -17,6 +17,7 @@
 		"test:uglified": "node test/uglified",
 		"posttest": "npx npm@\">= 10.2\" audit --production",
 		"lint": "eslint --ext=js,mjs .",
+		"postlint": "tsc && attw -P",
 		"version": "auto-changelog && git add CHANGELOG.md",
 		"postversion": "auto-changelog && git add CHANGELOG.md && git commit --no-edit --amend && git tag -f \"v$(node -e \"console.log(require('./package.json').version)\")\""
 	},
@@ -48,7 +49,12 @@
 		"safe-regex-test": "^1.1.0"
 	},
 	"devDependencies": {
+		"@arethetypeswrong/cli": "^0.17.2",
 		"@ljharb/eslint-config": "^21.1.1",
+		"@ljharb/tsconfig": "^0.2.3",
+		"@types/for-each": "^0.3.3",
+		"@types/make-generator-function": "^2.0.3",
+		"@types/tape": "^5.8.0",
 		"auto-changelog": "^2.5.0",
 		"core-js": "^2.6.5 || ^3.20.0",
 		"encoding": "^0.1.13",
@@ -60,6 +66,7 @@
 		"nyc": "^10.3.2",
 		"safe-publish-latest": "^2.0.0",
 		"tape": "^5.9.0",
+		"typescript": "next",
 		"uglify-register": "^1.0.1"
 	},
 	"testling": {
diff --git a/test/corejs.js b/test/corejs.js
index 73f0c89..3cc109c 100644
--- a/test/corejs.js
+++ b/test/corejs.js
@@ -1,5 +1,6 @@
 'use strict';
 
+// @ts-ignore
 require('core-js');
 
 require('./');
diff --git a/test/index.js b/test/index.js
index 355bbf2..038f2a1 100644
--- a/test/index.js
+++ b/test/index.js
@@ -58,6 +58,7 @@ test('returns false for non-generator function with faked toString', function (t
 
 test('returns false for non-generator function with faked @@toStringTag', { skip: !hasToStringTag || generatorFuncs.length === 0 }, function (t) {
 	var generatorFunc = generatorFuncs[0];
+	/** @type {{ toString(): unknown; valueOf(): unknown; [Symbol.toStringTag]?: unknown; }} */
 	var fakeGenFunction = {
 		toString: function () { return String(generatorFunc); },
 		valueOf: function () { return generatorFunc; }
diff --git a/test/uglified.js b/test/uglified.js
index fd82b55..91c0545 100644
--- a/test/uglified.js
+++ b/test/uglified.js
@@ -1,5 +1,6 @@
 'use strict';
 
+// @ts-ignore
 require('uglify-register/api').register({
 	exclude: [/\/node_modules\//, /\/test\//],
 	uglify: { mangle: true }
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..4bd3528
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,9 @@
+{
+  "extends": "@ljharb/tsconfig",
+  "compilerOptions": {
+    "maxNodeModuleJsDepth": 0
+  },
+  "exclude": [
+    "coverage"
+  ]
+}