Package reference

Mirrors the package README (single source). Install @basaltkit/exports-xlsx v1.0.3 — npm · source.

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@basaltkit/exports-xlsx

XLSX formatter for @basaltkit/exports: writes a valid .xlsx (Office Open XML) — zero dependencies. Bring your own Excel writer without dragging in heavy libraries. You need this module when users want to export to Excel, not just CSV.

What this module solves

.xlsx is, at its core, a ZIP of XML files. Instead of relying on a large library (exceljs, xlsx), this package writes the ZIP (STORE method + CRC32) and the SpreadsheetML by hand — a single-sheet .xlsx file, with headers, strings, and numbers. It plugs into @basaltkit/exports's formatter pipeline.

Installation

pnpm add @basaltkit/exports-xlsx @basaltkit/exports

No runtime dependencies beyond @basaltkit/exports (only for the formatter type).

Usage

Register the formatter with @basaltkit/exports and use the 'xlsx' format:

import { exportsPlugin, defineExport } from '@basaltkit/exports'
import { xlsxFormatter } from '@basaltkit/exports-xlsx'

exportsPlugin({ formatters: [xlsxFormatter] })

const usersExport = defineExport<{ name: string; joinedAt: Date }>({
  name: 'users',
  columns: [
    { header: 'Name', value: (u) => u.name },
    { header: 'Joined', value: (u) => u.joinedAt },
  ],
})

const { content, filename, contentType } = await exports.run(usersExport, users, 'xlsx')
// content: Buffer (an .xlsx), filename: 'users.xlsx',
// contentType: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'

Or use the formatter directly:

const buffer = xlsxFormatter.render(['Name', 'Price'], [['Ada', 29], ['Bob', 0]])

Details

• Numbers become numeric cells; dates become ISO text; everything else becomes an inline string (with XML escaping). null/undefined produce empty cells.
• One sheet (Sheet1). The ZIP uses the STORE method (no compression) — valid and opens fine in Excel/LibreOffice.
• Buffer-only: the whole workbook is built in memory (the ZIP needs each entry's size and CRC), so use exports.run(); exports.stream() rejects xlsx with ExportNotStreamableError.
• The produced Buffer passes unzip -t (correct CRCs) and opens in Excel/LibreOffice/Google Sheets.

How it connects to other modules

• @basaltkit/exports — this is a formatter for that package; the export definition comes from there.
• @basaltkit/queue + @basaltkit/files — generate the .xlsx in a job and store it for download (large reports).