main.tsx

import * as React from 'react'
import { createRoot } from 'react-dom/client'

import { useVirtualizer } from '@tanstack/react-virtual'
import {
  flexRender,
  getCoreRowModel,
  getSortedRowModel,
  useReactTable,
} from '@tanstack/react-table'
import { makeData } from './makeData'
import type { ColumnDef, SortingState } from '@tanstack/react-table'
import type { Person } from './makeData'
import './index.css'

function ReactTableVirtualized() {
  const [_sorting, setSorting] = React.useState<SortingState>([])
  const sorting = React.useDeferredValue(_sorting);

  const columns = React.useMemo<Array<ColumnDef<Person>>>(
    () => [
      {
        accessorKey: 'id',
        header: 'ID',
        size: 60,
      },
      {
        accessorKey: 'firstName',
        cell: (info) => info.getValue(),
      },
      {
        accessorFn: (row) => row.lastName,
        id: 'lastName',
        cell: (info) => info.getValue(),
        header: () => <span>Last Name</span>,
      },
      {
        accessorKey: 'age',
        header: () => 'Age',
        size: 50,
      },
      {
        accessorKey: 'visits',
        header: () => <span>Visits</span>,
        size: 50,
      },
      {
        accessorKey: 'status',
        header: 'Status',
      },
      {
        accessorKey: 'progress',
        header: 'Profile Progress',
        size: 80,
      },
      {
        accessorKey: 'createdAt',
        header: 'Created At',
        cell: (info) => info.getValue<Date>().toLocaleString(),
      },
    ],
    [],
  )

  const [data] = React.useState(() => makeData(50_000))

  const table = useReactTable({
    data,
    columns,
    state: {
      sorting,
    },
    onSortingChange: setSorting,
    getCoreRowModel: getCoreRowModel(),
    getSortedRowModel: getSortedRowModel(),
    debugTable: true,
  })

  const { rows } = table.getRowModel()

  const parentRef = React.useRef<HTMLDivElement>(null)

  const virtualizer = useVirtualizer({
    count: rows.length,
    getScrollElement: () => parentRef.current,
    estimateSize: () => 34,
    overscan: 20,
  })

  return (
    <div ref={parentRef} className="container">
      <div style={{ height: `${virtualizer.getTotalSize()}px` }}>
        <table>
          <thead>
            {table.getHeaderGroups().map((headerGroup) => (
              <tr key={headerGroup.id}>
                {headerGroup.headers.map((header) => {
                  return (
                    <th
                      key={header.id}
                      colSpan={header.colSpan}
                      style={{ width: header.getSize() }}
                    >
                      {header.isPlaceholder ? null : (
                        <div
                          {...{
                            className: header.column.getCanSort()
                              ? 'cursor-pointer select-none'
                              : '',
                            onClick: header.column.getToggleSortingHandler(),
                          }}
                        >
                          {flexRender(
                            header.column.columnDef.header,
                            header.getContext(),
                          )}
                          {{
                            asc: ' 🔼',
                            desc: ' 🔽',
                          }[header.column.getIsSorted() as string] ?? null}
                        </div>
                      )}
                    </th>
                  )
                })}
              </tr>
            ))}
          </thead>
          <tbody>
            {virtualizer.getVirtualItems().map((virtualRow, index) => {
              const row = rows[virtualRow.index]
              return (
                <tr
                  key={row.id}
                  style={{
                    height: `${virtualRow.size}px`,
                    transform: `translateY(${
                      virtualRow.start - index * virtualRow.size
                    }px)`,
                  }}
                >
                  {row.getVisibleCells().map((cell) => {
                    return (
                      <td key={cell.id}>
                        {flexRender(
                          cell.column.columnDef.cell,
                          cell.getContext(),
                        )}
                      </td>
                    )
                  })}
                </tr>
              )
            })}
          </tbody>
        </table>
      </div>
    </div>
  )
}

function App() {
  return (
    <div>
      <p>
        For tables, the basis for the offset of the translate css function is
        from the row's initial position itself. Because of this, we need to
        calculate the translateY pixel count differently and base it off the
        index.
      </p>
      <ReactTableVirtualized />
      <br />
      <br />
      {process.env.NODE_ENV === 'development' ? (
        <p>
          <strong>Notice:</strong> You are currently running React in
          development mode. Rendering performance will be slightly degraded
          until this application is built for production.
        </p>
      ) : null}
    </div>
  )
}

const container = document.getElementById('root')
const root = createRoot(container!)
const { StrictMode } = React

root.render(
  <StrictMode>
    <App />
  </StrictMode>,
)