Writing options

Pass these options to write, writeXLSX, writeFile, writeFileXLSX, or writeFileAsync. The file helpers can infer a format from the filename; in-memory serialization has no filename, so choose bookType explicitly for clarity.

Output representation and format

Option	Type / default	Effect
type	string	Select the representation returned by write
bookType	format identifier; "xlsx"	Select the output format. writeFile can infer it from the filename
sheet	string or zero-based number	Choose a sheet for single-sheet formats; default is the first sheet

type	Result
"buffer"	Node Buffer
"array"	Uint8Array
"base64"	Base64 text
"binary"	Binary string with one character per byte
"string"	Plain text; only for text formats
"file"	File-oriented mode; use writeFile instead

See Supported formats for bookType values. The output type and file format are separate choices: XLSX can be returned as base64, for example, but it cannot be returned as plain text.

const XLSX = require("@agent-sheet/wasm");
const assert = require("node:assert/strict");
const workbook = XLSX.utils.book_new();
XLSX.utils.book_append_sheet(workbook, XLSX.utils.aoa_to_sheet([["Label", "Amount"], ["Fees", 25]]), "Costs");
const base64 = XLSX.write(workbook, { type: "base64", bookType: "xlsx" });
assert.equal(XLSX.read(base64, { type: "base64" }).Sheets.Costs.B2.v, 25);
const csv = XLSX.write(workbook, { type: "string", bookType: "csv", FS: ";" });
assert.ok(csv.includes("Label;Amount"));

Package encoding

Option	Type	Effect
compression	boolean	Deflate ZIP entries for XLSX, XLSM, XLSB and ODS
bookSST	boolean	Emit a shared string table; needed for rich text in XLS/XLSB
themeXLSX	string	Supply replacement theme XML for XLSX/XLSM/XLSB
codepage	number	Choose a legacy text encoding where the format supports it
numbers	string	Supply the Numbers payload from dist/xlsx.zahl.js; required for bookType: "numbers"

Compression changes storage size, not the workbook’s cell values. A shared string table can change size and write time; it is not required for ordinary XLSX text cells.

Cells and document properties

Option	Type / default	Effect
cellStyles	boolean	Write styles and supported presentation metadata
cellDates	boolean	Write native date cells in XLSX/XLSM
ignoreEC	boolean; true	Suppress spreadsheet warnings about numbers stored as text
Props	properties object	Write these document properties instead of wb.Props
bookVBA	boolean	Re-emit wb.vbaraw in a macro-capable format such as XLSM
bookImages	boolean	Request image output where supported
sheetStubs	boolean	Shared compatibility option for blank stub cells

Properties include Title, Subject, Author, Manager, Company, Category, Keywords, Comments, LastAuthor, and CreatedDate.

const XLSX = require("@agent-sheet/wasm");
const assert = require("node:assert/strict");
const workbook = XLSX.utils.book_new();
const sheet = XLSX.utils.aoa_to_sheet([["Invoice"]]);
sheet.A1.s = { bold: true };
XLSX.utils.book_append_sheet(workbook, sheet, "Cover");
const bytes = XLSX.write(workbook, {
  type: "buffer", bookType: "xlsx", cellStyles: true,
  Props: { Title: "June invoice", Author: "Billing" }
});
const result = XLSX.read(bytes, { cellStyles: true });
assert.equal(result.Props.Title, "June invoice");
assert.ok(result.Sheets.Cover.A1.s.bold);

A write option does not guarantee that every metadata feature round-trips in every format. See Print settings and Pivot tables for their APIs. For existing workbooks, template mode preserves package features outside the ordinary workbook model.

Text output

Option	Type	Effect
FS	string	Field separator for CSV/text
RS	string	Record separator for CSV/text

For additional sheet-conversion controls such as forceQuotes, skipHidden, strip, or blankrows, use utils.sheet_to_csv and its options. See Converting sheets.

Template output

Set template: true to write using the original package retained by a template: true read. This is for XLSX/XLSM. Do not pass it to a newly constructed workbook and expect an original package to exist.

Use template helpers to record edits. Direct changes to arbitrary wb.Sheets fields are not a substitute for the helpers. Untouched package parts remain preserved.

Compatibility options

Option	Behavior
WTF	Request errors for malformed or unsupported content
password	Accepted in the declarations; encrypted output is not available
PPI	Screen density for converting wpx/hpx sizes: 72, 96 (default), 120, 144, "osx" or "win"

Protection flags and worksheet passwords are not file encryption. See Protection.