把箭头放在菜单下方——或布局中的任何位置

箭头不是内置装饰——它们是你传入的组件，因此摆放位置是布局决策，而非库的设置。此示例完全不传入 LeftArrow 或 RightArrow，而是在行下方的 Footer 插槽中渲染两个按钮，就在普通内容旁边。

箭头位于行下方——它们读取同一个 VisibilityContext，因此在两端仍会禁用。

工作原理

ScrollMenu 接受一个 Footer 组件，并在滚动容器下方渲染它，与项目同处一个 VisibilityContext.Provider 之内。该 story 的 footer 是一个普通的 flex div，里面有一些文本和这两个箭头按钮。因为 context 能抵达它，每个按钮都会调用 React.useContext(VisibilityContext)，并得到与侧边插槽完全相同的 API——箭头本身没有任何改变。

箭头状态，一如既往

useLeftArrowVisible() 与 useRightArrowVisible() 报告这一行是否已经位于该端；story 把结果映射到 disabled 并将按钮淡出。点击调用 scrollPrev() 与 scrollNext()。这些逻辑对按钮挂载在哪里一无所知，也不关心。

注意

Header 是行上方的镜像插槽，契约相同。
侧边的 LeftArrow/RightArrow 属性只是预先摆放好的变体——同样的箭头组件放哪个位置都能用。
footer 并不仅限箭头：任何读取 VisibilityContext 的组件在那里都有完整 API。
该 story 的 onWheel 处理器用鼠标滚轮分页，把触控板手势留给原生滚动。

完整源码

完整且可直接复制粘贴——这正是背后这份文件的可在 Storybook 中实时编辑的版本.

BottomArrows.source.tsx

import 'react-horizontal-scrolling-menu/dist/styles.css';

import styled from '@emotion/styled';
import React from 'react';
import {
  type publicApiType,
  ScrollMenu,
  VisibilityContext,
} from 'react-horizontal-scrolling-menu';

export function BottomArrows() {
  const [items] = React.useState(() => getItems());
  const [selected, setSelected] = React.useState<string[]>([]);

  const isItemSelected = (id: string): boolean =>
    !!selected.find((el) => el === id);

  const handleItemClick = (itemId: string) => {
    const itemSelected = isItemSelected(itemId);

    setSelected((currentSelected: string[]) =>
      itemSelected
        ? currentSelected.filter((el) => el !== itemId)
        : currentSelected.concat(itemId),
    );
  };

  return (
    <NoScrollbar>
      <ScrollMenu Footer={Arrows} onWheel={onWheel}>
        {items.map(({ id }) => (
          <Card
            title={id}
            itemId={id} // NOTE: itemId is required for track items
            key={id}
            onClick={() => handleItemClick(id)}
            selected={isItemSelected(id)}
          />
        ))}
      </ScrollMenu>
    </NoScrollbar>
  );
}
export default BottomArrows;

const NoScrollbar = styled('div')({
  '& .react-horizontal-scrolling-menu--scroll-container::-webkit-scrollbar': {
    display: 'none',
  },
  '& .react-horizontal-scrolling-menu--scroll-container': {
    scrollbarWidth: 'none',
    '-ms-overflow-style': 'none',
  },
});

const Arrows = () => (
  <div
    style={{
      width: '100%',
      display: 'flex',
      justifyContent: 'center',
    }}
  >
    Some other content
    <div style={{ marginLeft: '10px', display: 'flex' }}>
      <LeftArrow /> <RightArrow />
    </div>
  </div>
);

function LeftArrow() {
  const visibility = React.useContext<publicApiType>(VisibilityContext);

  const disabled = visibility.useLeftArrowVisible();

  return (
    <Arrow
      disabled={disabled}
      onClick={() => visibility.scrollPrev()}
      testId="left-arrow"
    >
      Left
    </Arrow>
  );
}

function RightArrow() {
  const visibility = React.useContext<publicApiType>(VisibilityContext);

  const disabled = visibility.useRightArrowVisible();

  return (
    <Arrow
      disabled={disabled}
      onClick={() => visibility.scrollNext()}
      testId="right-arrow"
    >
      Right
    </Arrow>
  );
}

function Arrow({
  children,
  disabled,
  onClick,
  className,
  testId,
}: {
  children: React.ReactNode;
  disabled: boolean;
  onClick: VoidFunction;
  className?: string;
  testId: string;
}) {
  return (
    <ArrowButton
      disabled={disabled}
      onClick={onClick}
      className={'arrow' + `-${className}`}
      data-testid={testId}
    >
      {children}
    </ArrowButton>
  );
}
const ArrowButton = styled('button')((props) => ({
  cursor: 'pointer',
  display: 'flex',
  flexDirection: 'column',
  justifyContent: 'center',
  marginBottom: '2px',
  opacity: props.disabled ? '0' : '1',
  userSelect: 'none',
  borderRadius: '6px',
  borderWidth: '1px',
}));

function Card({
  onClick,
  selected,
  title,
  itemId,
}: {
  onClick: (context: publicApiType) => void;
  selected: boolean;
  title: string;
  itemId: string;
}) {
  const visibility = React.useContext<publicApiType>(VisibilityContext);
  const isVisible = visibility.useIsVisible(itemId, true);

  return (
    <CardBody
      data-cy={itemId}
      onClick={() => onClick(visibility)}
      onKeyDown={(ev: React.KeyboardEvent) => {
        ev.code === 'Enter' && onClick(visibility);
      }}
      data-testid="card"
      role="button"
      tabIndex={0}
      className="card"
      visible={isVisible}
      selected={selected}
    >
      <div className="header">
        <div>{title}</div>
        <div className="visible">visible: {JSON.stringify(isVisible)}</div>
        <div className="selected">selected: {JSON.stringify(!!selected)}</div>
      </div>
      <div className="background" />
    </CardBody>
  );
}
const CardBody = styled('div')<{ selected?: boolean; visible?: boolean }>(
  (props) => ({
    border: '1px solid',
    display: 'inline-block',
    margin: '0 10px',
    width: '160px',
    userSelect: 'none',
    borderRadius: '8px',
    overflow: 'hidden',

    '& .header': {
      backgroundColor: 'white',
    },

    '& .visible': {
      backgroundColor: props.visible ? 'transparent' : 'gray',
    },

    '& .background': {
      backgroundColor: props.selected ? 'green' : 'bisque',
      height: '200px',
    },
  }),
);

const getId = (index: number) => `${'test'}${index}`;

const getItems = () =>
  Array(10)
    .fill(0)
    .map((_, ind) => ({ id: getId(ind) }));

function onWheel(apiObj: publicApiType, ev: React.WheelEvent): void {
  // NOTE: no good standart way to distinguish touchpad scrolling gestures
  // but can assume that gesture will affect X axis, mouse scroll only Y axis
  // of if deltaY too small probably is it touchpad
  const isThouchpad = Math.abs(ev.deltaX) !== 0 || Math.abs(ev.deltaY) < 15;

  if (isThouchpad) {
    ev.stopPropagation();
    return;
  }

  if (ev.deltaY < 0) {
    apiObj.scrollNext();
  } else {
    apiObj.scrollPrev();
  }
}

把箭头放在菜单下方——或布局中的任何位置

工作原理

箭头状态，一如既往

注意

完整源码

相关示例