feat(useSet): add toggle a method

docs/useSet.md

@@ -8,7 +8,7 @@ React state hook that tracks a [Set](https://developer.mozilla.org/en-US/docs/We
 import {useSet} from 'react-use';
 
 const Demo = () => {
-  const [set, { add, has, remove, reset }] = useSet(new Set(['hello']));
+  const [set, { add, has, remove, toggle, reset }] = useSet(new Set(['hello']));
 
   return (
     <div>
@@ -17,6 +17,9 @@ const Demo = () => {
       <button onClick={() => remove('hello')} disabled={!has('hello')}>
         Remove 'hello'
       </button>
+      <button onClick={() => toggle('hello')}>
+        {has('hello') ? 'Remove' : 'Add'} hello
+      </button>
       <pre>{JSON.stringify(Array.from(set), null, 2)}</pre>
     </div>
   );

src/useSet.ts

@@ -3,6 +3,7 @@ import { useState, useMemo, useCallback } from 'react';
 export interface StableActions<K> {
   add: (key: K) => void;
   remove: (key: K) => void;
+  toggle: (key: K) => void;
   reset: () => void;
 }
 
@@ -13,14 +14,13 @@ export interface Actions<K> extends StableActions<K> {
 const useSet = <K>(initialSet = new Set<K>()): [Set<K>, Actions<K>] => {
   const [set, setSet] = useState(initialSet);
 
-  const stableActions = useMemo<StableActions<K>>(
-    () => ({
-      add: item => setSet(prevSet => new Set([...Array.from(prevSet), item])),
-      remove: item => setSet(prevSet => new Set(Array.from(prevSet).filter(i => i !== item))),
-      reset: () => setSet(initialSet),
-    }),
-    [setSet]
-  );
+  const stableActions = useMemo<StableActions<K>>(() => {
+    const add = (item: K) => setSet(prevSet => new Set([...Array.from(prevSet), item]));
+    const remove = (item: K) => setSet(prevSet => new Set(Array.from(prevSet).filter(i => i !== item)));
+    const toggle = (item: K) => (set.has(item) ? remove : add)(item);
+
+    return { add, remove, toggle, reset: () => setSet(initialSet) };
+  }, [setSet]);
 
   const utils = {
     has: useCallback(item => set.has(item), [set]),

tests/useSet.test.ts

@@ -12,6 +12,7 @@ it('should init set and utils', () => {
     has: expect.any(Function),
     add: expect.any(Function),
     remove: expect.any(Function),
+    toggle: expect.any(Function),
     reset: expect.any(Function),
   });
 });
@@ -94,6 +95,28 @@ it('should remove existing key', () => {
   expect(result.current[0]).toEqual(new Set([1]));
 });
 
+it('should remove an existing key on toggle', () => {
+  const { result } = setUp(new Set([1, 2]));
+  const [, utils] = result.current;
+
+  act(() => {
+    utils.toggle(2);
+  });
+
+  expect(result.current[0]).toEqual(new Set([1]));
+});
+
+it('should add a new key on toggle', () => {
+  const { result } = setUp(new Set([1]));
+  const [, utils] = result.current;
+
+  act(() => {
+    utils.toggle(2);
+  });
+
+  expect(result.current[0]).toEqual(new Set([1, 2]));
+});
+
 it('should do nothing if removing non-existing key', () => {
   const { result } = setUp(new Set(['a', 'b']));
   const [, utils] = result.current;