Top-level API

Load the package as const XLSX = require("@agent-sheet/wasm"). In an ES module, use import XLSX from "@agent-sheet/wasm". Node does not support named imports from this CommonJS package.

The spreadsheet engine is a WebAssembly module embedded in the JavaScript files. Parsing and serialization are synchronous. writeFileAsync is the exception for file I/O: it serializes synchronously, then writes the file asynchronously.

Read

Signature	Parameters and behavior	Returns
`read(data, options?)`	Parse text, binary strings, base64, `Buffer`, `Uint8Array`, `ArrayBuffer` or byte arrays. `options.type` selects the representation. Detects the spreadsheet format from content.	A workbook
`readFile(filename, options?)`	Read a file from disk and parse it. Node only. `filename` is a path.	A workbook
`readFileSync(filename, options?)`	Alias of `readFile`.	A workbook

options is a ParsingOptions object. The result normally has SheetNames (names in display order) and Sheets (worksheets keyed by name). Metadata-only read options may omit worksheet data.

const XLSX = require("@agent-sheet/wasm");
const assert = require("node:assert/strict");
const workbook = XLSX.read("Product,Quantity\nPens,12", { type: "string" });
assert.deepEqual(workbook.SheetNames, ["Sheet1"]);
assert.equal(workbook.Sheets.Sheet1.B2.v, 12);

See Reading files for partial reads and dense worksheets.

Serialize in memory

Signature	Parameters and behavior	Returns
`write(workbook, options)`	Serialize a workbook. `bookType` chooses the format; `type` chooses the representation.	Data in the requested representation
`writeXLSX(workbook, options)`	XLSX-specific serialization. Use for XLSX output.	Data in the requested representation

Use type: "buffer" for a Node Buffer, "array" for a Uint8Array, "base64" for base64 text, or "binary" for a binary string. "string" is for text formats such as CSV, not XLSX. See WritingOptions.

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([["Total", 42]]), "Summary");
const bytes = XLSX.write(workbook, { type: "buffer", bookType: "xlsx" });
assert.ok(Buffer.isBuffer(bytes));
assert.equal(XLSX.read(bytes).Sheets.Summary.B1.v, 42);

Write files

Signature	Parameters and behavior	Returns
`writeFile(workbook, filename, options?)`	Save to disk in Node; start a download in browsers. If `bookType` is absent, infer the format from the filename.	No result to consume
`writeFileSync(workbook, filename, options?)`	Alias of `writeFile`; it does not add browser filesystem access.	No result to consume
`writeFileXLSX(workbook, filename, options?)`	XLSX-specific file output.	No result to consume
`writeFileAsync(filename, workbook, options?, callback)`	Node file output with callback completion. Notice that the filename comes first. Serialization is synchronous; file I/O is asynchronous.	No result to consume; use the callback

The callback follows Node’s file-write convention: check the error argument. Serialization errors can be thrown before the callback is scheduled. This function does not return a Promise. With no options, use writeFileAsync(filename, workbook, callback).

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([[7]]), "Data");
XLSX.writeFileAsync("async.xlsx", workbook, { bookType: "xlsx" }, (error) => {
  if (error) throw error;
  assert.equal(XLSX.readFile("async.xlsx").Sheets.Data.A1.v, 7);
});

See Writing files for format selection and metadata limits.

Configuration

Signature or property	Meaning	Returns
`version`	Compatibility API version (`2.20260615.1`), independent of the npm release version.	A string
`set_fs(fs)`	Register a Node-compatible filesystem module for file helpers. Useful when a bundler does not provide it automatically.	No result to consume
`set_cptable(table)`	Register codepage tables, such as the package’s `dist/cpexcel.js` export.	No result to consume
`set_date_style(format)`	Compatibility helper that changes built-in date format 14. Prefer explicit formats or `SSF` locale configuration for new code.	No result to consume
`cycle_width(width)`	Round a width to a value representable by spreadsheet file formats. Input is in spreadsheet width units, not pixels.	A number

These settings apply to the library instance in the current JavaScript realm. A worker has its own instance. Register locale settings before a read if you want generated cell text (w) to use them.

Lower-level parsers

Prefer read unless you already have a container from another API.

Signature	Parameters	Returns
`parse_xlscfb(container, options?)`	A CFB container holding a BIFF workbook, plus parsing options. Not present in the mini distribution.	A workbook
`parse_zip(zip, options?)`	An already extracted ZIP object in the shape expected by the library, plus parsing options. It is not an API for arbitrary ZIP libraries’ objects.	A workbook

Namespaces

utils: worksheet creation, conversion, addresses, styles and cells.
Template helpers: edits to an existing XLSX/XLSM package.
SSF: number and date formatting.
CFB: compound-file containers.
stream: Node readable output streams.

Encryption and compatibility

File encryption is not available. utils.hash_password and utils.test_password appear in the declarations for compatibility with the original @sheet/edit package, but are absent at runtime. Worksheet protection is a different feature; see Protection.