import _ from "lodash";
import React, { useEffect, useState } from "react";
import { listData } from "./data";
type ListType = {
  itemHeight?: number; // 每一項(xiàng)的高度
  visibleHeight?: number; // 可見高度
  total?: number; // 數(shù)據(jù)總數(shù)
  dataSource?: any[]; // 全部數(shù)據(jù)
};
// 為了看效果我模擬的數(shù)據(jù)
const myList = Array.from(Array(1000), (item, index) => ({name: `名字${item}`, id: index}));
const List = (props: ListType) => {
  const {
    itemHeight = 54,
    visibleHeight = 540,
    total = 130,
    dataSource = myList,
  } = props;
  const [showData, setShowData] = useState<any>([]);
  const [offset, setOffset] = useState<any>({ top: 0, bottom: 0 });
  const visibleCount = Math.ceil(visibleHeight / itemHeight);
  useEffect(() => {
    const list = _.slice(dataSource, 0, visibleCount);
    const bottom = (total - visibleCount) * itemHeight;
    setOffset({ top: 0, bottom });
    setShowData(list);
  }, [dataSource]);
  const onScroll = (event: React.UIEvent<HTMLDivElement>) => {
    const target = event.currentTarget;
    const startIdx = Math.floor(target.scrollTop / itemHeight);
    const endIdx = startIdx + visibleCount;
    setShowData(dataSource.slice(startIdx, endIdx));
    const top = startIdx * itemHeight;
    const bottom = (total - endIdx) * itemHeight;
    setOffset({ top, bottom });
  };
  return (
    <div
      className="virtual"
      style={{
        height: visibleHeight,
        width: "100%",
        overflow: "auto",
        border: "1px solid #d9d9d9",
      }}
      onScroll={onScroll} // 在父元素上添加滾動(dòng)事件監(jiān)聽
    >
      {/* 可視數(shù)據(jù) 為了滾動(dòng)數(shù)據(jù)一直在可視區(qū)。加上頂部偏移 */}
      <div style={{ height: visibleHeight, marginTop: offset.top }}>
        {_.map(showData, (item, index: any) => {
          return (
            <div
              style={{
                display: "flex",
                alignItems: "center",
                height: itemHeight,
                borderBottom: "1px solid #d9d9d9",
              }}
              key={index}
            >
              {item.name}
            </div>
          );
        })}
      </div>
      {/* 底部占位 */}
      <div style={{ height: offset.bottom }} />
    </div>
  );
};
export default List;

import React, { useEffect, useRef, useState } from "react";
import { Table } from "antd";
import _ from "lodash";
type TableType = {
  itemHeight?: number; // 每一項(xiàng)的高度
  visibleHeight?: number; // 可見高度
  total?: number; // 數(shù)據(jù)總數(shù)
  dataSource?: any[]; // 全部數(shù)據(jù)
};
// 為了看效果我模擬的數(shù)據(jù)
const myList = Array.from(Array(1000), (item, index) => ({name: `名字${item}`, id: index}));
const VirtualTable = (props: TableType) => {
  const {
    itemHeight = 54,
    visibleHeight = 540,
    total = 130,
    dataSource = myList,
  } = props;
  const [point, setPoint] = useState<any>([0, 20]);
  const [offset, setOffset] = useState<any>({top:0, bottom: 0 });
  const tabRef = useRef<any>();
  const containRef = useRef<any>();
  const visibleCount = Math.ceil(visibleHeight / itemHeight);
  useEffect(() => {
    const bottom = (total - visibleCount) * itemHeight;
    setOffset({ bottom });
    setPoint([0, visibleCount]);
    const scrollDom = tabRef?.current?.querySelector(".ant-table-body");
    console.log("aaa",scrollDom);
    if (scrollDom) {
      containRef.current = scrollDom;
      containRef.current.addEventListener("scroll", onScroll);
      return () => {
        containRef.current.removeEventListener("scroll", onScroll);
      };
    }
  }, [myList]);
  const onScroll = (e: any) => {
    const startIdx = Math.floor(e?.target?.scrollTop / itemHeight);
    const endIdx = startIdx + visibleCount;
    const bottom = (total - endIdx) * itemHeight;
    const top = startIdx * itemHeight;
    setOffset({top,bottom});
    setPoint([startIdx, endIdx]);
  };
  const columns = [
    { title: "ID", dataIndex: "id", width: 150 },
    { title: "名字", dataIndex: "name", width: 150 },
  ];
  return (
    <Table
      ref={tabRef}
      className="virtual-table"
      pagination={false}
      columns={columns}
      dataSource={dataSource}
      scroll={{ y: visibleHeight }}
      components={{
        body: {
          wrapper: ({ className, children }: any) => {
            return (
              <tbody className={className}>
                {children?.[0]}
                <tr style={{height: offset.top}}/>
                {_.slice(children?.[1], point?.[0], point?.[1])}
                <tr style={{height: offset.bottom}}></tr>
              </tbody>
            );
          },
        },
      }}
    />
  );
};
export default VirtualTable;