[New] add types

Author: ljharb

getInferredName.d.ts

@@ -0,0 +1,5 @@
+declare function getInferredName(key: PropertyKey): string;
+
+declare const x: typeof getInferredName | undefined | null;
+
+export = x;

getInferredName.js

@@ -1,10 +1,13 @@
 'use strict';
 
+/** @type {NonNullable<import('./getInferredName')> | undefined} */
 var getInferredName;
 try {
-	// eslint-disable-next-line no-new-func
-	getInferredName = Function('s', 'return { [s]() {} }[s].name;');
+	// eslint-disable-next-line no-new-func, no-extra-parens
+	getInferredName = /** @type {NonNullable<import('./getInferredName')>} */ (Function('s', 'return { [s]() {} }[s].name;'));
 } catch (e) {}
 
 var inferred = function () {};
+
+/** @type {import('./getInferredName')} */
 module.exports = getInferredName && inferred.name === 'inferred' ? getInferredName : null;

index.d.ts

@@ -0,0 +1,3 @@
+declare function getSymbolDescription(thisArg: symbol | Symbol): string | undefined;
+
+export = getSymbolDescription;

index.js

@@ -6,12 +6,16 @@ var callBound = require('call-bound');
 
 var $SyntaxError = require('es-errors/syntax');
 var getGlobalSymbolDescription = GetIntrinsic('%Symbol.keyFor%', true);
+/** @type {undefined | ((thisArg: symbol | Symbol) => symbol)} */
 var thisSymbolValue = callBound('%Symbol.prototype.valueOf%', true);
+/** @type {undefined | ((thisArg: symbol | Symbol) => string)} */
 var symToStr = callBound('Symbol.prototype.toString', true);
+/** @type {(thisArg: string, start?: number, end?: number) => string} */
 var $strSlice = callBound('String.prototype.slice');
 
 var getInferredName = require('./getInferredName');
 
+/** @type {import('.')} */
 /* eslint-disable consistent-return */
 module.exports = callBound('%Symbol.prototype.description%', true) || function getSymbolDescription(symbol) {
 	if (!thisSymbolValue) {
@@ -37,7 +41,8 @@ module.exports = callBound('%Symbol.prototype.description%', true) || function g
 		}
 	}
 
-	desc = $strSlice(symToStr(sym), 7, -1); // str.slice('Symbol('.length, -')'.length);
+	// eslint-disable-next-line no-extra-parens
+	desc = $strSlice(/** @type {NonNullable<typeof symToStr>} */ (symToStr)(sym), 7, -1); // str.slice('Symbol('.length, -')'.length);
 	if (desc) {
 		return desc;
 	}

package.json

@@ -12,8 +12,9 @@
 		"prepack": "npmignore --auto --commentLines=autogenerated",
 		"prepublish": "not-in-publish || npm run prepublishOnly",
 		"prepublishOnly": "safe-publish-latest",
+		"prelint": "evalmd README.md",
 		"lint": "eslint --ext=.js,.mjs .",
-		"postlint": "evalmd README.md",
+		"postlint": "tsc && attw -P",
 		"pretest": "npm run lint",
 		"tests-only": "nyc tape 'test/**/*.js'",
 		"test": "npm run tests-only",
@@ -46,7 +47,13 @@
 		"get-intrinsic": "^1.2.6"
 	},
 	"devDependencies": {
+		"@arethetypeswrong/cli": "^0.17.1",
 		"@ljharb/eslint-config": "^21.1.1",
+		"@ljharb/tsconfig": "^0.2.2",
+		"@types/for-each": "^0.3.3",
+		"@types/get-intrinsic": "^1.2.3",
+		"@types/object-inspect": "^1.13.0",
+		"@types/tape": "^5.7.0",
 		"auto-changelog": "^2.5.0",
 		"encoding": "^0.1.13",
 		"es-value-fixtures": "^1.5.0",
@@ -59,7 +66,8 @@
 		"nyc": "^10.3.2",
 		"object-inspect": "^1.13.3",
 		"safe-publish-latest": "^2.0.0",
-		"tape": "^5.9.0"
+		"tape": "^5.9.0",
+		"typescript": "^5.8.0-dev.20241216"
 	},
 	"engines": {
 		"node": ">= 0.4"

test/index.js

@@ -12,6 +12,7 @@ var getInferredName = require('../getInferredName');
 test('getSymbolDescription', function (t) {
 	t.test('no symbols', { skip: v.hasSymbols }, function (st) {
 		st['throws'](
+			// @ts-expect-error
 			getSymbolDescription,
 			SyntaxError,
 			'requires Symbol support'
@@ -20,7 +21,11 @@ test('getSymbolDescription', function (t) {
 		st.end();
 	});
 
-	forEach(v.nonSymbolPrimitives.concat(v.objects), function (nonSymbol) {
+	forEach([].concat(
+		// @ts-expect-error TS sucks with concat
+		v.nonSymbolPrimitives,
+		v.objects
+	), function (nonSymbol) {
 		t['throws'](
 			function () { getSymbolDescription(nonSymbol); },
 			v.hasSymbols ? TypeError : SyntaxError,
@@ -30,13 +35,15 @@ test('getSymbolDescription', function (t) {
 
 	t.test('with symbols', { skip: !v.hasSymbols }, function (st) {
 		forEach(
-			[
+			// eslint-disable-next-line no-extra-parens
+			/** @type {[symbol, undefined | string][]} */ ([
 				[Symbol(), undefined],
 				[Symbol(undefined), undefined],
+				// @ts-expect-error
 				[Symbol(null), 'null'],
 				[Symbol.iterator, 'Symbol.iterator'],
 				[Symbol('foo'), 'foo']
-			],
+			]),
 			function (pair) {
 				var sym = pair[0];
 				var desc = pair[1];

tsconfig.json

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