快速入门：React 中的横向滚动菜单

最小的可用配置：一行卡片、两个箭头按钮，以及本库真正要做的——每张卡片都知道自己是否在屏幕上。一个组件、一个必需属性、一次样式表导入。

The code on the left, running:

滚动这一行——箭头在两端禁用，每张卡片都追踪自己的可见性。

工作原理

ScrollMenu 在一个原生滚动容器里渲染你的子元素，并用 IntersectionObserver 观察每一个。唯一的契约是 itemId——每个子元素上的唯一属性，项目正是靠它被追踪、找到和滚动到。在任何子元素或箭头内部，VisibilityContext 都会把完整 API 交给你。

可见性 hook

卡片调用 useIsVisible(itemId) 订阅自己的在屏状态——没有滚动监听、没有位置计算，可见性变化时只有受影响的卡片会重新渲染。箭头用 first 与 last 这两个简写在行的两端自行禁用。

注意

styles.css 是单独的导入——JS 包绝不会注入 CSS。
项目的宽度是你自己的 CSS；菜单不做任何测量，只附带 210 字节的布局样式。
useIsVisible(itemId, true) 的第二个参数是观察器报告之前使用的值——如果你服务端渲染这个菜单，它就是服务端渲染出的值。

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.

Simple.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 SimpleExample() {
  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 (
    <div>
      <div>
        <NoScrollbar>
          <ScrollMenu
            LeftArrow={LeftArrow}
            RightArrow={RightArrow}
            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>
      </div>

      <div style={{ height: '300vh', backgroundColor: 'aqua', opacity: 0.2 }}>
        filler
      </div>
    </div>
  );
}

export default SimpleExample;

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',
  },
});

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();
  }
}

快速入门：React 中的横向滚动菜单

工作原理

可见性 hook

注意

完整源码

相关示例