Merge pull request #25 from streamich/get-set

Get set

README.md

@@ -54,6 +54,7 @@
   - [`useSpring`](./docs/useSpring.md) — interpolates number over time according to spring dynamics.
   - [`useTimeout`](./docs/useTimeout.md) — returns true after a timeout.
   - [`useTween`](./docs/useTween.md) — re-renders component, while tweening a number from 0 to 1. [![][img-demo]](https://codesandbox.io/s/52990wwzyl)
+  - [`useUpdate`](./docs/useUpdate.md) — returns a callback, which re-renders component when called.
     <br/>
     <br/>
 - [**Side-effects**](./docs/Side-effects.md)
@@ -71,6 +72,7 @@
     <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.

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>
+  );
+};
+```

docs/useUpdate.md

@@ -0,0 +1,21 @@
+# `useUpdate`
+
+React utility hook that returns a function that forces component
+to re-render when called.
+
+
+## Usage
+
+```jsx
+import {useUpdate} from 'react-use';
+
+const Demo = () => {
+  const update = useUpdate();
+  return (
+    <>
+      <div>Time: {Date.now()}</div>
+      <button onClick={update}>Update</button>
+    </>
+  );
+};
+```

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/>
+  )

src/__stories__/useUpdate.story.tsx

@@ -0,0 +1,21 @@
+import {storiesOf} from '@storybook/react';
+import * as React from 'react';
+import {useUpdate} from '..';
+import ShowDocs from '../util/ShowDocs';
+
+const Demo = () => {
+  const update = useUpdate();
+  return (
+    <>
+      <div>Time: {Date.now()}</div>
+      <button onClick={update}>Update</button>
+    </>
+  );
+};
+
+storiesOf('useUpdate', module)
+  .add('Docs', () => <ShowDocs md={require('../../docs/useUpdate.md')} />)
+  .add('Demo', () =>
+    <Demo/>
+  )
+

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';
@@ -30,6 +31,7 @@ import useTitle from './useTitle';
 import useToggle from './useToggle';
 import useTween from './useTween';
 import useUnmount from './useUnmount';
+import useUpdate from './useUpdate';
 import useWindowSize from './useWindowSize';
 
 export {
@@ -40,6 +42,7 @@ export {
   useCss,
   useFavicon,
   useGeolocation,
+  useGetSet,
   useHover,
   useIdle,
   useLifecycles,
@@ -65,5 +68,6 @@ export {
   useToggle,
   useTween,
   useUnmount,
+  useUpdate,
   useWindowSize,
 };

src/useGetSet.ts

@@ -0,0 +1,17 @@
+import {useRef} from './react';
+import useUpdate from './useUpdate';
+
+const useGetSet = <T>(initialValue: T): [() => T, (value: T) => void] => {
+  const update = useUpdate();
+  let state = useRef(initialValue);
+
+  const get = () => state.current;
+  const set = (value: T) => {
+    state.current = value;
+    update();
+  };
+
+  return [get, set];
+};
+
+export default useGetSet;

src/useUpdate.ts

@@ -0,0 +1,5 @@
+import {useState} from './react';
+
+const useUpdate = () => useState(0)[1] as (() => void);
+
+export default useUpdate;