createColumnHelper

function createColumnHelper<TData extends RowData>(): ColumnHelper<TData>

Returns a type-safe column definition builder. The helper provides four methods:

.accessor(accessorKeyOrFn, options)

Define a column that reads data from each row.

Key accessor:

const col = columnHelper.accessor('name', {
  header: 'Name',
  enableSorting: true,
})
// Infers: accessorKey = 'name', value type = TData['name']

Function accessor:

const col = columnHelper.accessor((row) => `${row.firstName} ${row.lastName}`, {
  id: 'fullName',
  header: 'Full Name',
})

.display(options)

Define a non-data column (actions, checkboxes, etc.). Requires an id.

const col = columnHelper.display({
  id: 'actions',
  header: 'Actions',
  cell: ({ row }) => `<button>Edit ${row.original.name}</button>`,
})

.group(options)

Define a column group header that contains child columns.

const col = columnHelper.group({
  id: 'contact',
  header: 'Contact Info',
  columns: [
    columnHelper.accessor('email', { header: 'Email' }),
    columnHelper.accessor('phone', { header: 'Phone' }),
  ],
})

.columns(columnList)

Normalize a heterogeneous column list into ColumnDef<TData, unknown>[].

Each .accessor(...) returns a ColumnDef<TData, TValue> with a concrete, per-column value type. Because TValue is invariant, an inline array mixing string, number, and boolean columns infers as a union that does not assign to ColumnDef<TData, unknown>[], forcing an as ColumnDef<TData, unknown> cast on nearly every column. Wrap the array in .columns([...]) to erase the per-column TValue in one place:

const columns = columnHelper.columns([
  columnHelper.accessor('name', { header: 'Name' }), // TValue = string
  columnHelper.accessor('age', { header: 'Age' }), // TValue = number
  columnHelper.accessor('active', { header: 'Active' }), // TValue = boolean
  columnHelper.display({ id: 'actions', header: 'Actions' }),
])
// columns: ColumnDef<Person, unknown>[] — no per-column casts

It returns a fresh array (safe to mutate) and preserves element identity and order.

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