perf: skipping re-rendering

src/Filler.tsx

@@ -1,6 +1,6 @@
-import * as React from 'react';
-import ResizeObserver from 'rc-resize-observer';
 import classNames from 'classnames';
+import ResizeObserver from 'rc-resize-observer';
+import * as React from 'react';
 
 export type InnerProps = Pick<React.HTMLAttributes<HTMLDivElement>, 'role' | 'id'>;
 
@@ -69,15 +69,15 @@ const Filler = React.forwardRef(
       };
     }
 
+    const handleResize = ({ offsetHeight }) => {
+      if (offsetHeight && onInnerResize) {
+        onInnerResize();
+      }
+    };
+
     return (
       <div style={outerStyle}>
-        <ResizeObserver
-          onResize={({ offsetHeight }) => {
-            if (offsetHeight && onInnerResize) {
-              onInnerResize();
-            }
-          }}
-        >
+        <ResizeObserver onResize={handleResize}>
           <div
             style={innerStyle}
             className={classNames({

src/List.tsx

@@ -18,7 +18,7 @@ import useOriginScroll from './hooks/useOriginScroll';
 import useScrollDrag from './hooks/useScrollDrag';
 import type { ScrollPos, ScrollTarget } from './hooks/useScrollTo';
 import useScrollTo from './hooks/useScrollTo';
-import type { ExtraRenderInfo, GetKey, RenderFunc, SharedConfig } from './interface';
+import type { ExtraRenderInfo, GetKey, RenderFunc } from './interface';
 import type { ScrollBarDirectionType, ScrollBarRef } from './ScrollBar';
 import ScrollBar from './ScrollBar';
 import { getSpinSize } from './utils/scrollbarUtil';
@@ -165,10 +165,6 @@ export function RawList<T>(props: ListProps<T>, ref: React.Ref<ListRef>) {
     setScrollMoving(false);
   };
 
-  const sharedConfig: SharedConfig<T> = {
-    getKey,
-  };
-
   // ================================ Scroll ================================
   function syncScrollTop(newTop: number | ((prev: number) => number)) {
     setOffsetTop((origin) => {
@@ -572,7 +568,7 @@ export function RawList<T>(props: ListProps<T>, ref: React.Ref<ListRef>) {
     offsetLeft,
     setInstanceRef,
     children,
-    sharedConfig,
+    getKey,
   );
 
   let componentStyle: React.CSSProperties = null;

src/hooks/useChildren.tsx

@@ -1,5 +1,5 @@
 import * as React from 'react';
-import type { RenderFunc, SharedConfig } from '../interface';
+import type { RenderFunc, GetKey } from '../interface';
 import { Item } from '../Item';
 
 export default function useChildren<T>(
@@ -10,22 +10,25 @@ export default function useChildren<T>(
   offsetX: number,
   setNodeRef: (item: T, element: HTMLElement) => void,
   renderFunc: RenderFunc<T>,
-  { getKey }: SharedConfig<T>,
+  getKey: GetKey<T>,
 ) {
-  return list.slice(startIndex, endIndex + 1).map((item, index) => {
-    const eleIndex = startIndex + index;
-    const node = renderFunc(item, eleIndex, {
-      style: {
-        width: scrollWidth,
-      },
-      offsetX,
-    }) as React.ReactElement;
+  // The list reference may remain unchanged, but its internal data may change, which can result in different behavior compared to the previous implementation.  
+  return React.useMemo(() => {
+    return list.slice(startIndex, endIndex + 1).map((item, index) => {
+      const eleIndex = startIndex + index;
+      const node = renderFunc(item, eleIndex, {
+        style: {
+          width: scrollWidth,
+        },
+        offsetX,
+      }) as React.ReactElement;
 
-    const key = getKey(item);
-    return (
-      <Item key={key} setRef={(ele) => setNodeRef(item, ele)}>
-        {node}
-      </Item>
-    );
-  });
+      const key = getKey(item);
+      return (
+        <Item key={key} setRef={(ele) => setNodeRef(item, ele)}>
+          {node}
+        </Item>
+      );
+    });
+  }, [list, startIndex, endIndex, setNodeRef, renderFunc, getKey, offsetX, scrollWidth]);
 }

src/hooks/useHeights.tsx

@@ -69,7 +69,7 @@ export default function useHeights<T>(
     }
   }
 
-  function setInstanceRef(item: T, instance: HTMLElement) {
+  const setInstanceRef = React.useCallback(function setInstanceRef(item: T, instance: HTMLElement) {
     const key = getKey(item);
     const origin = instanceRef.current.get(key);
 
@@ -88,11 +88,12 @@ export default function useHeights<T>(
         onItemRemove?.(item);
       }
     }
-  }
+  }, [getKey, onItemAdd, onItemRemove]);
 
   useEffect(() => {
     return cancelRaf;
   }, []);
 
+  // This is somewhat confusing: when heightsRef.current.set is called, updatedMark changes, which in turn causes heightsRef.current to also change.
   return [setInstanceRef, collectHeight, heightsRef.current, updatedMark];
 }

src/interface.ts

@@ -4,10 +4,6 @@ export type RenderFunc<T> = (
   props: { style: React.CSSProperties; offsetX: number },
 ) => React.ReactNode;
 
-export interface SharedConfig<T> {
-  getKey: (item: T) => React.Key;
-}
-
 export type GetKey<T> = (item: T) => React.Key;
 
 export type GetSize = (startKey: React.Key, endKey?: React.Key) => { top: number; bottom: number };

tests/props.test.js

@@ -1,5 +1,5 @@
-import React from 'react';
 import { mount } from 'enzyme';
+import React from 'react';
 import List from '../src';
 
 describe('Props', () => {
@@ -11,30 +11,20 @@ describe('Props', () => {
     }
 
     const wrapper = mount(
-      <List data={[{ id: 903 }, { id: 1128 }]} itemKey={item => item.id}>
+      <List data={[{ id: 903 }, { id: 1128 }]} itemKey={(item) => item.id}>
         {({ id }) => <ItemComponent>{id}</ItemComponent>}
       </List>,
     );
 
-    expect(
-      wrapper
-        .find('Item')
-        .at(0)
-        .key(),
-    ).toBe('903');
-
-    expect(
-      wrapper
-        .find('Item')
-        .at(1)
-        .key(),
-    ).toBe('1128');
+    expect(wrapper.find('Item').at(0).key()).toBe('903');
+
+    expect(wrapper.find('Item').at(1).key()).toBe('1128');
   });
 
   it('prefixCls', () => {
     const wrapper = mount(
-      <List data={[0]} itemKey={id => id} prefixCls="prefix">
-        {id => <div>{id}</div>}
+      <List data={[0]} itemKey={(id) => id} prefixCls="prefix">
+        {(id) => <div>{id}</div>}
       </List>,
     );
 
@@ -44,13 +34,40 @@ describe('Props', () => {
   it('offsetX in renderFn', () => {
     let scrollLeft;
     mount(
-      <List data={[0]} itemKey={id => id} prefixCls="prefix">
-        {(id, _, { offsetX }) => { 
+      <List data={[0]} itemKey={(id) => id} prefixCls="prefix">
+        {(id, _, { offsetX }) => {
           scrollLeft = offsetX;
-          return <div>{id}</div>}}
+          return <div>{id}</div>;
+        }}
       </List>,
     );
 
     expect(scrollLeft).toEqual(0);
   });
+
+  it('no unnecessary re-render', () => {
+    const renderItem = jest.fn();
+    renderItem.mockImplementation(({ id, key }) => <div key={key}>{id}</div>);
+
+    const data = [{ id: 1, key: 1 }];
+    function Wrapper() {
+      const [state, setState] = React.useState(0);
+
+      React.useEffect(() => {
+        setState(1);
+      }, []);
+
+      return (
+        <div>
+          <h1>{state}</h1>
+          <List data={data} itemKey="key" prefixCls="prefix">
+            {renderItem}
+          </List>
+        </div>
+      );
+    }
+    const wrapper = mount(<Wrapper />);
+    expect(wrapper.find('h1').text()).toBe('1');
+    expect(renderItem).toHaveBeenCalledTimes(1);
+  });
 });

tests/scroll-Firefox.test.js

@@ -1,9 +1,9 @@
-import React from 'react';
-import { act } from 'react-dom/test-utils';
+import { act } from '@testing-library/react';
 import { mount } from 'enzyme';
-import { spyElementPrototypes } from './utils/domHook';
+import React from 'react';
 import List from '../src';
 import isFF from '../src/utils/isFirefox';
+import { spyElementPrototypes } from './utils/domHook';
 
 function genData(count) {
   return new Array(count).fill(null).map((_, index) => ({ id: String(index) }));
@@ -124,8 +124,10 @@ describe('List.Firefox-Scroll', () => {
     const wrapper = genList({ itemHeight: 20, height: 100, data: genData(100), ref: listRef });
     const ulElement = wrapper.find('ul').instance();
     // scroll to bottom
-    listRef.current.scrollTo(99999);
-    jest.runAllTimers();
+    act(() => {
+      listRef.current.scrollTo(99999);
+      jest.runAllTimers();
+    });
     expect(wrapper.find('ul').instance().scrollTop).toEqual(1900);
 
     act(() => {

tests/scroll.test.js

@@ -94,9 +94,13 @@ describe('List.Scroll', () => {
     jest.useFakeTimers();
     const listRef = React.createRef();
     const wrapper = genList({ itemHeight: 20, height: 100, data: genData(100), ref: listRef });
-    jest.runAllTimers();
 
-    listRef.current.scrollTo(null);
+    act(() => {
+      jest.runAllTimers();
+
+      listRef.current.scrollTo(null);
+    });
+
     expect(wrapper.find('.rc-virtual-list-scrollbar-thumb').props().style.display).not.toEqual(
       'none',
     );
@@ -107,8 +111,10 @@ describe('List.Scroll', () => {
     it('value scroll', () => {
       const listRef = React.createRef();
       const wrapper = genList({ itemHeight: 20, height: 100, data: genData(100), ref: listRef });
-      listRef.current.scrollTo(903);
-      jest.runAllTimers();
+      act(() => {
+        listRef.current.scrollTo(903);
+        jest.runAllTimers();
+      });
       expect(wrapper.find('ul').instance().scrollTop).toEqual(903);
 
       wrapper.unmount();
@@ -125,9 +131,8 @@ describe('List.Scroll', () => {
         ...result,
         ref,
         scrollTo: (...args) => {
-          ref.current.scrollTo(...args);
-
           act(() => {
+            ref.current.scrollTo(...args);
             jest.runAllTimers();
           });
         },
@@ -153,8 +158,10 @@ describe('List.Scroll', () => {
 
     it('scroll top should not out of range', () => {
       const { scrollTo, container } = presetList();
-      scrollTo({ index: 0, align: 'bottom' });
-      jest.runAllTimers();
+      act(() => {
+        scrollTo({ index: 0, align: 'bottom' });
+        jest.runAllTimers();
+      });
       expect(container.querySelector('ul').scrollTop).toEqual(0);
     });
 
@@ -389,9 +396,13 @@ describe('List.Scroll', () => {
       ref: listRef,
       direction: 'rtl',
     });
-    jest.runAllTimers();
 
-    listRef.current.scrollTo(null);
+    act(() => {
+      jest.runAllTimers();
+
+      listRef.current.scrollTo(null);
+    });
+
     expect(wrapper.find('.rc-virtual-list-scrollbar-thumb').props().style.display).not.toEqual(
       'none',
     );

tests/scrollWidth.test.tsx

@@ -230,10 +230,14 @@ describe('List.scrollWidth', () => {
       ref: listRef,
     });
 
-    listRef.current.scrollTo({ left: 135 });
+    act(() => {
+      listRef.current.scrollTo({ left: 135 });
+    });
     expect(listRef.current.getScrollInfo()).toEqual({ x: 135, y: 0 });
 
-    listRef.current.scrollTo({ left: -99 });
+    act(() => {
+      listRef.current.scrollTo({ left: -99 });
+    });
     expect(listRef.current.getScrollInfo()).toEqual({ x: 0, y: 0 });
   });