zero-dep-xlsx

A tiny, zero-dependency XLSX (OOXML SpreadsheetML) writer for Node.

A .xlsx file is just a ZIP of XML parts. This library produces the ZIP and DEFLATE streams with Node's built-in zlib — no exceljs, no jszip, no native modules, nothing in node_modules.

Features

• Multiple worksheets in one workbook
• Per-column header text, width, and number format
• String, number, boolean, Date, and empty cells
• Per-row font styling (e.g. bold header)
• Dates written as Excel serial numbers using UTC components, so output is timezone-independent (no off-by-one local-timezone drift)

Install

npm install zero-dep-xlsx

Requires Node.js >= 18. Ships both ESM and CommonJS builds plus TypeScript type declarations — import and require both work, no extra @types package needed.

Usage

ESM / TypeScript

import { writeFileSync } from 'node:fs'
import { buildXlsx } from 'zero-dep-xlsx'

const buf = buildXlsx({
  creator: 'My App',
  sheets: [
    {
      name: 'People',
      columns: [
        { header: 'Name', key: 'name', width: 20 },
        { header: 'Score', key: 'score', width: 10, style: { numFmt: '0.00' } },
        { header: 'Joined', key: 'joined', width: 14, style: { numFmt: 'yyyy-mm-dd' } },
      ],
      rows: [
        { name: 'Ada', score: 99.5, joined: new Date('2024-01-15') },
        { name: 'Linus', score: 88, joined: new Date('2023-08-02') },
      ],
      // Make the header row (row 1) bold.
      rowStyles: [{ row: 1, font: { bold: true } }],
    },
  ],
})

writeFileSync('people.xlsx', buf)

CommonJS

const { writeFileSync } = require('node:fs')
const { buildXlsx } = require('zero-dep-xlsx')

const buf = buildXlsx({
  sheets: [
    {
      name: 'People',
      columns: [{ header: 'Name', key: 'name', width: 20 }],
      rows: [{ name: 'Ada' }],
    },
  ],
})

writeFileSync('people.xlsx', buf)

buildXlsx returns a Buffer containing the full .xlsx file, ready to write to disk or stream as an HTTP response.

API

buildXlsx(options) => Buffer

| Option | Type | Default | Description | | --------- | -------- | ---------------- | --------------------------------- | | creator | string | "zero-dep-xlsx"| Document author metadata | | created | Date | new Date() | Creation timestamp metadata | | sheets | Sheet[]| — | One or more worksheets (required) |

Sheet

{
  name: string
  columns: Array<{
    header: string
    key: string
    width?: number            // Excel character units, default 10
    style?: { numFmt?: string }
  }>
  rows: Array<Record<string, string | number | boolean | Date | null>>
  rowStyles?: Array<{
    row: number               // 1-based; row 1 is the header
    font?: { bold?: boolean; size?: number }
  }>
}

Cell values are mapped by column key. Number-format codes (numFmt) follow the standard Excel format syntax ("0.00", "#,##0", "yyyy-mm-dd", etc.).

Throws if sheets is missing or empty.

License

MIT