feat: useScrollbarWidth hook;

README.md

@@ -66,6 +66,7 @@
   - [`useWindowSize`](./docs/useWindowSize.md) — tracks `Window` dimensions. [![][img-demo]](https://codesandbox.io/s/m7ln22668)
   - [`useMeasure`](./docs/useMeasure.md) — tracks an HTML element's dimensions using the Resize Observer API.[![][img-demo]](https://streamich.github.io/react-use/?path=/story/sensors-usemeasure--demo)
   - [`createBreakpoint`](./docs/createBreakpoint.md) — tracks `innerWidth`
+  - [`useScrollbarWidth`](./docs/useScrollbarWidth.md) — detects browser's native scrollbars width. [![][img-demo]](https://streamich.github.io/react-use/?path=/story/sensors-usescrollbarwidth--demo)
     <br/>
     <br/>
 - [**UI**](./docs/UI.md)

docs/useScrollbarWidth.md

@@ -0,0 +1,25 @@
+# `useScrollbarWidth`
+
+Hook that will return current browser's scrollbar width.  
+In case hook been called before DOM ready, it will return `undefined` and will cause re-render on first available RAF.
+> **_NOTE:_** it does not work (return 0) for mobile devices, because their scrollbar width can not be determined.
+
+## Usage
+
+```jsx
+const Demo = () => {
+  const sbw = useScrollbarWidth();
+
+  return (
+    <div>
+      {sbw === undefined ? `DOM is not ready yet, SBW detection delayed` : `Browser's scrollbar width is ${sbw}px`}
+    </div>
+  );
+};
+```
+
+## Reference
+
+```typescript
+const sbw: number | undefined = useScrollbarWidth();
+```

package.json

@@ -46,6 +46,7 @@
   },
   "homepage": "https://github.com/streamich/react-use#readme",
   "dependencies": {
+    "@xobotyi/scrollbar-width": "1.5.0",
     "copy-to-clipboard": "^3.2.0",
     "nano-css": "^5.2.1",
     "react-fast-compare": "^2.0.4",

src/__stories__/useScrollbarWidth.story.tsx

@@ -0,0 +1,18 @@
+import { storiesOf } from '@storybook/react';
+import * as React from 'react';
+import { useScrollbarWidth } from '..';
+import ShowDocs from './util/ShowDocs';
+
+const Demo = () => {
+  const sbw = useScrollbarWidth();
+
+  return (
+    <div>
+      {sbw === undefined ? `DOM is not ready yet, SBW detection delayed` : `Browser's scrollbar width is ${sbw}px`}
+    </div>
+  );
+};
+
+storiesOf('Sensors/useScrollbarWidth', module)
+  .add('Docs', () => <ShowDocs md={require('../../docs/useScroll.md')} />)
+  .add('Demo', () => <Demo />);

src/index.ts

@@ -92,6 +92,7 @@ export { default as useUpsert } from './useUpsert';
 export { default as useVibrate } from './useVibrate';
 export { default as useVideo } from './useVideo';
 export { default as useStateValidator } from './useStateValidator';
+export { useScrollbarWidth } from './useScrollbarWidth';
 export { useMultiStateValidator } from './useMultiStateValidator';
 export { default as useWindowScroll } from './useWindowScroll';
 export { default as useWindowSize } from './useWindowSize';

src/useScrollbarWidth.ts

@@ -0,0 +1,21 @@
+import { scrollbarWidth } from '@xobotyi/scrollbar-width';
+import { useEffect, useState } from 'react';
+
+export function useScrollbarWidth(): number | undefined {
+  const [sbw, setSbw] = useState(scrollbarWidth());
+
+  // this needed to ensure the scrollbar width in case hook called before the DOM is ready
+  useEffect(() => {
+    if (typeof sbw !== 'undefined') {
+      return;
+    }
+
+    const raf = requestAnimationFrame(() => {
+      setSbw(scrollbarWidth());
+    });
+
+    return () => cancelAnimationFrame(raf);
+  }, []);
+
+  return sbw;
+}

tests/useScrollbarWidth.test.ts

@@ -0,0 +1,45 @@
+import { act, renderHook } from '@testing-library/react-hooks';
+import { scrollbarWidth } from '@xobotyi/scrollbar-width';
+import { useScrollbarWidth } from '../src';
+import { replaceRaf } from 'raf-stub';
+
+declare var requestAnimationFrame: {
+  add: (cb: Function) => number;
+  remove: (id: number) => void;
+  flush: (duration?: number) => void;
+  reset: () => void;
+  step: (steps?: number, duration?: number) => void;
+};
+
+describe('useScrollbarWidth', () => {
+  beforeAll(() => {
+    replaceRaf();
+  });
+
+  afterEach(() => {
+    requestAnimationFrame.reset();
+  });
+
+  it('should be defined', () => {
+    expect(useScrollbarWidth).toBeDefined();
+  });
+
+  it('should return value of scrollbarWidth result', () => {
+    scrollbarWidth.__cache = 21;
+    const { result } = renderHook(() => useScrollbarWidth());
+
+    expect(result.current).toBe(21);
+  });
+
+  it('should re-call scrollbar width in RAF in case `scrollbarWidth()` returned undefined', () => {
+    scrollbarWidth.__cache = undefined;
+    const { result } = renderHook(() => useScrollbarWidth());
+    expect(result.current).toBe(undefined);
+    scrollbarWidth.__cache = 34;
+    act(() => {
+      requestAnimationFrame.step();
+    });
+
+    expect(result.current).toBe(34);
+  });
+});

yarn.lock

@@ -3094,6 +3094,11 @@
     "@webassemblyjs/wast-parser" "1.8.5"
     "@xtuc/long" "4.2.2"
 
+"@xobotyi/scrollbar-width@1.5.0":
+  version "1.5.0"
+  resolved "https://registry.yarnpkg.com/@xobotyi/scrollbar-width/-/scrollbar-width-1.5.0.tgz#488210bff634548040dc22a72f62722a85b134e1"
+  integrity sha512-BK+HR1D00F2xh7n4+5en8/dMkG13uvIXLmEbsjtc1702b7+VwXkvlBDKoRPJMbkRN5hD7VqWa3nS9fNT8JG3CA==
+
 "@xtuc/ieee754@^1.2.0":
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/@xtuc/ieee754/-/ieee754-1.2.0.tgz#eef014a3145ae477a1cbc00cd1e552336dceb790"