CFB container API

XLSX.CFB works with Compound File Binary containers used by legacy Office formats. Container operations do not convert worksheet cells. For spreadsheet input/output, use XLSX.read and XLSX.write instead.

The namespace is typed as any in the bundled declarations. A container has parallel FullPaths and FileIndex arrays. Stream entries have a name, type, size and byte content; storage/root entries represent directories.

Read, find and write

Signature	Parameters and semantics	Returns
`read(data, options?)`	Parse data according to `options.type`; default input representation is base64	Container
`parse(bytes, options?)`	Parse raw byte input; for ZIP input, supply an options object even if empty	Container
`find(container, path)`	Find a stream/storage entry by container path	Entry, or `null` if absent
`write(container, options?)`	Serialize a container; default output representation is buffer	Serialized data
`writeFile(container, filename, options?)`	Serialize and save a file in Node	No result to consume
`version`	Container-library version	String

Input type values include "base64", "binary", "buffer", "array", and "file". File input reads a Node filesystem path. Unlike top-level XLSX.read, prefer an explicit type for a clear container-input contract.

Output type can be "buffer", "array", "binary", "base64", or "file". File mode uses options.filename; prefer writeFile for clarity. fileType chooses a container representation such as "cfb" or "zip"; compression: true requests ZIP compression. Reading a ZIP container here does not automatically parse it as a spreadsheet workbook.

const XLSX = require("@agent-sheet/wasm");
const assert = require("node:assert/strict");
const CFB = XLSX.CFB;
const container = CFB.utils.cfb_new();
CFB.utils.cfb_add(container, "note.txt", Buffer.from("Hello", "utf8"));
const bytes = CFB.write(container, { type: "buffer" });
const result = CFB.read(bytes, { type: "buffer" });
const entry = CFB.find(result, "note.txt");
assert.equal(Buffer.from(entry.content).toString("utf8"), "Hello");
assert.equal(CFB.find(result, "missing.txt"), null);

Container utilities

These functions are under XLSX.CFB.utils.

Signature	Parameters and semantics	Returns
`cfb_new(options?)`	Create an empty container; `root` can name the root storage	Container
`cfb_add(container, path, content, options?)`	Add or replace a stream at `path` using byte content	Stream entry
`cfb_del(container, path)`	Delete a matching entry	Boolean indicating success
`cfb_mov(container, oldPath, newPath)`	Rename/move an entry	Boolean indicating success
`cfb_gc(container)`	Rebuild container ordering and directory metadata after changes	No result to consume

These operations mutate the container. Use paths relative to its root, such as "documents/note.txt". cfb_add can take entry options such as creation and modification dates. Writing performs the container preparation needed for output.

const XLSX = require("@agent-sheet/wasm");
const assert = require("node:assert/strict");
const CFB = XLSX.CFB;
const container = CFB.utils.cfb_new();
CFB.utils.cfb_add(container, "draft.txt", Buffer.from("Draft"));
assert.equal(CFB.utils.cfb_mov(container, "draft.txt", "final.txt"), true);
assert.equal(CFB.find(container, "final.txt").name, "final.txt");
assert.equal(CFB.utils.cfb_del(container, "final.txt"), true);
assert.equal(CFB.find(container, "final.txt"), null);

Byte utilities

These are low-level utilities, not workbook functions:

Signature	Meaning	Returns
`bconcat(chunks)`	Concatenate byte chunks	Byte data
`prep_blob(blob, position)`	Add cursor-based read/write methods to a byte object and set its starting cursor	No result to consume
`ReadShift(size, type?)`	Read from a prepared byte object’s cursor; call as its method	Decoded value
`CheckField(hex, field?)`	Check bytes at the current cursor against expected hex	No result to consume; throws on mismatch
`use_zlib(zlib)`	Supply compatible Node zlib routines for compression	No result to consume

utils.consts exposes CFB sector and entry-type constants. Underscore-prefixed compression routines are also exposed; prefer container read/write options over calling them directly.

Scope and limits

CFB does not provide encrypted-workbook support. Preserving a macro stream is not the same as executing it. To parse a BIFF workbook already stored in a CFB container, the full distribution offers XLSX.parse_xlscfb(container, options); this parser is absent from mini. See Top-level API.