Preact Example: Column Groups

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import { useReducer, useState } from 'preact/hooks'
import { render } from 'preact'
import './index.css'
import {
  createColumnHelper,
  tableFeatures,
  useTable,
} from '@tanstack/preact-table'
import { makeData } from './makeData'
import type { Person } from './makeData'

const features = tableFeatures({})

const columnHelper = createColumnHelper<typeof features, Person>()

// use new columnHelper.columns method to create columns with the same TValue generic so TypeScript doesn't complain when passing columns to useTable
const columns = columnHelper.columns([
  columnHelper.group({
    id: 'hello',
    header: () => <span>Hello</span>,
    columns: columnHelper.columns([
      columnHelper.accessor('firstName', {
        cell: (info) => info.getValue(),
        footer: (props) => props.column.id,
      }),
      columnHelper.accessor((row) => row.lastName, {
        id: 'lastName',
        cell: (info) => info.getValue(),
        header: () => <span>Last Name</span>,
        footer: (props) => props.column.id,
      }),
    ]),
  }),
  columnHelper.group({
    header: 'Info',
    footer: (props) => props.column.id,
    columns: columnHelper.columns([
      columnHelper.accessor('age', {
        header: () => 'Age',
        footer: (props) => props.column.id,
      }),
      columnHelper.group({
        header: 'More Info',
        columns: columnHelper.columns([
          columnHelper.accessor('visits', {
            header: () => <span>Visits</span>,
            footer: (props) => props.column.id,
          }),
          columnHelper.accessor('status', {
            header: 'Status',
            footer: (props) => props.column.id,
          }),
          columnHelper.accessor('progress', {
            header: 'Profile Progress',
            footer: (props) => props.column.id,
          }),
        ]),
      }),
    ]),
  }),
])

function App() {
  const [data, setData] = useState(() => makeData(20))
  const refreshData = () => setData(makeData(20))
  const stressTest = () => setData(makeData(1_000))
  const rerender = useReducer(() => ({}), {})[1]

  const table = useTable(
    {
      debugTable: true,
      features,
      columns,
      data,
    },
    (state) => state, // default selector
  )

  return (
    <div className="demo-root">
      <div>
        <button onClick={() => refreshData()}>Regenerate Data</button>
        <button onClick={() => stressTest()}>Stress Test (1k rows)</button>
      </div>
      <table>
        <thead>
          {table.getHeaderGroups().map((headerGroup) => (
            <tr key={headerGroup.id}>
              {headerGroup.headers.map((header) => (
                <th key={header.id} colSpan={header.colSpan}>
                  {header.isPlaceholder ? null : (
                    <table.FlexRender header={header} />
                  )}
                </th>
              ))}
            </tr>
          ))}
        </thead>
        <tbody>
          {table.getRowModel().rows.map((row) => (
            <tr key={row.id}>
              {row.getAllCells().map((cell) => (
                <td key={cell.id}>
                  <table.FlexRender cell={cell} />
                </td>
              ))}
            </tr>
          ))}
        </tbody>
        <tfoot>
          {table.getFooterGroups().map((footerGroup) => (
            <tr key={footerGroup.id}>
              {footerGroup.headers.map((header) => (
                <th key={header.id} colSpan={header.colSpan}>
                  {header.isPlaceholder ? null : (
                    <table.FlexRender footer={header} />
                  )}
                </th>
              ))}
            </tr>
          ))}
        </tfoot>
      </table>
      <div className="spacer-md" />
      <button onClick={() => rerender(0)} className="demo-button">
        Rerender
      </button>
    </div>
  )
}

const rootElement = document.getElementById('root')
if (!rootElement) throw new Error('Failed to find the root element')

render(<App />, rootElement)