feat: 🎸 add useGetSet hook

Author: streamich

Diff for: README.md

@@ -71,6 +71,7 @@
     <br/>
     <br/>
 - [**State**](./docs/State.md)
+  - [`useGetSet`](./docs/useGetSet.md) &mdash; returns state getter `get()` instead of raw state.
   - [`useObservable`](./docs/useObservable.md) &mdash; tracks latest value of an `Observable`.
   - [`useSetState`](./docs/useSetState.md) &mdash; creates `setState` method which works like `this.setState`. [![][img-demo]](https://codesandbox.io/s/n75zqn1xp0)
   - [`useToggle`](./docs/useToggle.md) &mdash; tracks state of a boolean.

Diff for: docs/useGetSet.md

@@ -0,0 +1,46 @@
+# `useGetSet`
+
+React state hook that returns state getter function instead of
+raw state itself, this prevents subtle bugs when state is used
+in nested functions.
+
+
+## Usage
+
+Below example uses `useGetSet` to increment a number after 1 second
+on each click.
+
+```jsx
+import {useGetSet} from 'react-use';
+
+const Demo = () => {
+  const [get, set] = useGetSet(0);
+  const onClick = () => {
+    setTimeout(() => {
+      set(get() + 1)
+    }, 1_000);
+  };
+
+  return (
+    <button onClick={onClick}>Clicked: {get()}</button>
+  );
+};
+```
+
+If you would do this example in a naive way using regular `useState`
+hook, the counter would not increment correctly if you click fast multiple times.
+
+```jsx
+const DemoWrong = () => {
+  const [cnt, set] = useState(0);
+  const onClick = () => {
+    setTimeout(() => {
+      set(cnt + 1)
+    }, 1_000);
+  };
+
+  return (
+    <button onClick={onClick}>Clicked: {cnt}</button>
+  );
+};
+```

Diff for: src/__stories__/useGetSet.story.tsx

@@ -0,0 +1,40 @@
+import * as React from 'react';
+import {storiesOf} from '@storybook/react';
+import {useGetSet} from '..';
+import {useState} from '../react';
+import ShowDocs from '../util/ShowDocs';
+
+const Demo = () => {
+  const [get, set] = useGetSet(0);
+  const onClick = () => {
+    setTimeout(() => {
+      set(get() + 1)
+    }, 1_000);
+  };
+
+  return (
+    <button onClick={onClick}>Clicked: {get()}</button>
+  );
+};
+
+const DemoWrong = () => {
+  const [cnt, set] = useState(0);
+  const onClick = () => {
+    setTimeout(() => {
+      set(cnt + 1)
+    }, 1_000);
+  };
+
+  return (
+    <button onClick={onClick}>Clicked: {cnt}</button>
+  );
+};
+
+storiesOf('useGetSet', module)
+  .add('Docs', () => <ShowDocs md={require('../../docs/useGetSet.md')} />)
+  .add('Demo', () =>
+    <Demo/>
+  )
+  .add('DemoWrong', () =>
+    <DemoWrong/>
+  )

Diff for: src/index.ts

@@ -5,6 +5,7 @@ import useCounter from './useCounter';
 import useCss from './useCss';
 import useFavicon from './useFavicon';
 import useGeolocation from './useGeolocation';
+import useGetSet from './useGetSet';
 import useHover from './useHover';
 import useIdle from './useIdle';
 import useLifecycles from './useLifecycles';
@@ -40,6 +41,7 @@ export {
   useCss,
   useFavicon,
   useGeolocation,
+  useGetSet,
   useHover,
   useIdle,
   useLifecycles,

Diff for: src/useGetSet.ts

@@ -0,0 +1,16 @@
+import {useState, useRef} from './react';
+
+const useGetSet = <T>(initialValue: T): [() => T, (value: T) => void] => {
+  const [_, update] = useState(undefined);
+  let state = useRef(initialValue);
+
+  const get = () => state.current;
+  const set = (value: T) => {
+    state.current = value;
+    update(undefined);
+  };
+
+  return [get, set];
+};
+
+export default useGetSet;