[New] add types

index.d.ts

@@ -0,0 +1,3 @@
+declare function isNumberObject(value: unknown): value is (number | Number);
+
+export = isNumberObject;

index.js

@@ -4,6 +4,7 @@ var callBound = require('call-bind/callBound');
 
 var $numToStr = callBound('Number.prototype.toString');
 
+/** @type {import('.')} */
 var tryNumberObject = function tryNumberObject(value) {
 	try {
 		$numToStr(value);
@@ -16,6 +17,7 @@ var $toString = callBound('Object.prototype.toString');
 var numClass = '[object Number]';
 var hasToStringTag = require('has-tostringtag/shams')();
 
+/** @type {import('.')} */
 module.exports = function isNumberObject(value) {
 	if (typeof value === 'number') {
 		return true;

package.json

@@ -18,6 +18,7 @@
 		"posttest": "npx npm@'>=10.2' audit --production",
 		"prelint": "eclint check $(git ls-files | xargs find 2> /dev/null | grep -vE 'node_modules|\\.git')",
 		"lint": "eslint --ext=js,mjs .",
+		"postlint": "tsc -p . && attw -P",
 		"version": "auto-changelog && git add CHANGELOG.md",
 		"postversion": "auto-changelog && git add CHANGELOG.md && git commit --no-edit --amend && git tag -f \"v$(node -e \"console.log(require('./package.json').version)\")\""
 	},
@@ -42,7 +43,12 @@
 		"has-tostringtag": "^1.0.2"
 	},
 	"devDependencies": {
+		"@arethetypeswrong/cli": "^0.17.0",
 		"@ljharb/eslint-config": "^21.1.1",
+		"@ljharb/tsconfig": "^0.2.0",
+		"@types/call-bind": "^1.0.5",
+		"@types/core-js": "^2.5.8",
+		"@types/tape": "^5.6.5",
 		"auto-changelog": "^2.5.0",
 		"core-js": "^3.39.0",
 		"eclint": "^2.8.1",
@@ -54,25 +60,11 @@
 		"npmignore": "^0.3.1",
 		"nyc": "^10.3.2",
 		"safe-publish-latest": "^2.0.0",
-		"tape": "^5.9.0"
+		"tape": "^5.9.0",
+		"typescript": "next"
 	},
 	"testling": {
-		"files": "test/index.js",
-		"browsers": [
-			"iexplore/6.0..latest",
-			"firefox/3.0..6.0",
-			"firefox/15.0..latest",
-			"firefox/nightly",
-			"chrome/4.0..10.0",
-			"chrome/20.0..latest",
-			"chrome/canary",
-			"opera/10.0..latest",
-			"opera/next",
-			"safari/4.0..latest",
-			"ipad/6.0..latest",
-			"iphone/6.0..latest",
-			"android-browser/4.2"
-		]
+		"files": "test/index.js"
 	},
 	"engines": {
 		"node": ">= 0.4"

test/index.js

@@ -5,6 +5,7 @@ var isNumber = require('../');
 var hasToStringTag = require('has-tostringtag/shams')();
 
 test('not Numbers', function (t) {
+	// @ts-expect-error
 	t.notOk(isNumber(), 'undefined is not Number');
 	t.notOk(isNumber(null), 'null is not Number');
 	t.notOk(isNumber(false), 'false is not Number');
@@ -20,6 +21,7 @@ test('not Numbers', function (t) {
 });
 
 test('@@toStringTag', { skip: !hasToStringTag }, function (t) {
+	/** @type {{ toString(): string; valueOf(): number; [Symbol.toStringTag]?: string; }} */
 	var fakeNumber = {
 		toString: function () { return '7'; },
 		valueOf: function () { return 42; }

tsconfig.json

@@ -0,0 +1,9 @@
+{
+	"extends": "@ljharb/tsconfig",
+	"compilerOptions": {
+		"target": "ES2021",
+	},
+	"exclude": [
+		"coverage"
+	]
+}