Add .weakRef() (#165)

Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>

readme.md

@@ -198,6 +198,7 @@ is.boundFunction(function () {});
 ##### .set(value)
 ##### .weakMap(value)
 ##### .weakSet(value)
+##### .weakRef(value)
 
 #### Typed arrays
 

source/index.ts

@@ -1,5 +1,5 @@
 import type {Buffer} from 'node:buffer';
-import type {Class, Falsy, TypedArray, ObservableLike, Primitive} from './types.js';
+import type {Class, Falsy, TypedArray, ObservableLike, Primitive, WeakRef} from './types.js';
 
 const typedArrayTypeNames = [
 	'Int8Array',
@@ -40,6 +40,7 @@ const objectTypeNames = [
 	'Set',
 	'WeakMap',
 	'WeakSet',
+	'WeakRef',
 	'ArrayBuffer',
 	'SharedArrayBuffer',
 	'DataView',
@@ -230,6 +231,8 @@ is.weakMap = <Key extends object = object, Value = unknown>(value: unknown): val
 
 is.weakSet = (value: unknown): value is WeakSet<object> => isObjectOfType<WeakSet<object>>('WeakSet')(value); // eslint-disable-line @typescript-eslint/ban-types
 
+is.weakRef = (value: unknown): value is WeakRef<object> => isObjectOfType<WeakRef<object>>('WeakRef')(value); // eslint-disable-line @typescript-eslint/ban-types
+
 is.int8Array = isObjectOfType<Int8Array>('Int8Array');
 is.uint8Array = isObjectOfType<Uint8Array>('Uint8Array');
 is.uint8ClampedArray = isObjectOfType<Uint8ClampedArray>('Uint8ClampedArray');
@@ -524,6 +527,7 @@ interface Assert {
 	set: <T = unknown>(value: unknown) => asserts value is Set<T>;
 	weakMap: <Key extends object = object, Value = unknown>(value: unknown) => asserts value is WeakMap<Key, Value>; // eslint-disable-line @typescript-eslint/ban-types
 	weakSet: <T extends object = object>(value: unknown) => asserts value is WeakSet<T>; // eslint-disable-line @typescript-eslint/ban-types
+	weakRef: <T extends object = object>(value: unknown) => asserts value is WeakRef<T>; // eslint-disable-line @typescript-eslint/ban-types
 	int8Array: (value: unknown) => asserts value is Int8Array;
 	uint8Array: (value: unknown) => asserts value is Uint8Array;
 	uint8ClampedArray: (value: unknown) => asserts value is Uint8ClampedArray;
@@ -629,6 +633,7 @@ export const assert: Assert = {
 	set: <T = unknown>(value: unknown): asserts value is Set<T> => assertType(is.set(value), 'Set', value),
 	weakMap: <Key extends object = object, Value = unknown>(value: unknown): asserts value is WeakMap<Key, Value> => assertType(is.weakMap(value), 'WeakMap', value), // eslint-disable-line @typescript-eslint/ban-types
 	weakSet: <T extends object = object>(value: unknown): asserts value is WeakSet<T> => assertType(is.weakSet(value), 'WeakSet', value), // eslint-disable-line @typescript-eslint/ban-types
+	weakRef: <T extends object = object>(value: unknown): asserts value is WeakRef<T> => assertType(is.weakRef(value), 'WeakRef', value), // eslint-disable-line @typescript-eslint/ban-types
 	int8Array: (value: unknown): asserts value is Int8Array => assertType(is.int8Array(value), 'Int8Array', value),
 	uint8Array: (value: unknown): asserts value is Uint8Array => assertType(is.uint8Array(value), 'Uint8Array', value),
 	uint8ClampedArray: (value: unknown): asserts value is Uint8ClampedArray => assertType(is.uint8ClampedArray(value), 'Uint8ClampedArray', value),

source/types.ts

@@ -49,3 +49,8 @@ export interface ObservableLike {
 
 // eslint-disable-next-line @typescript-eslint/ban-types
 export type Falsy = false | 0 | 0n | '' | null | undefined;
+
+export interface WeakRef<T extends object> { // eslint-disable-line @typescript-eslint/ban-types
+	readonly [Symbol.toStringTag]: 'WeakRef';
+	deref(): T | undefined;
+}

test/test.ts

@@ -336,6 +336,12 @@ const types = new Map<string, Test>([
 		],
 		typename: 'WeakSet',
 	}],
+	['weakRef', {
+		is: is.weakRef,
+		assert: assert.weakRef,
+		fixtures: window.WeakRef ? [new window.WeakRef({})] : [],
+		typename: 'WeakRef',
+	}],
 	['weakMap', {
 		is: is.weakMap,
 		assert: assert.weakMap,
@@ -798,6 +804,10 @@ test('is.weakSet', t => {
 	testType(t, 'weakSet');
 });
 
+test('is.weakRef', t => {
+	testType(t, 'weakRef');
+});
+
 test('is.int8Array', t => {
 	testType(t, 'int8Array');
 });
@@ -1223,7 +1233,7 @@ test('is.arrayLike', t => {
 	t.false(is.arrayLike(new Map()));
 
 	(function () {
-		t.notThrows(() => {
+		t.notThrows(function () {
 			assert.arrayLike(arguments); // eslint-disable-line prefer-rest-params
 		});
 	})();