SheetJS Spreadsheet data parser and writer

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0.11.126 years ago6 years agoMinified + gzip package size for codenautas-xlsx in KB


Parser and writer for various spreadsheet formats. Pure-JS cleanroom implementation from official specifications, related documents, and test files. Emphasis on parsing and writing robustness, cross-format feature compatibility with a unified JS representation, and ES3/ES5 browser compatibility back to IE6.
This is the community version. We also offer a pro version with performance enhancements, additional features by request, and dedicated support.
Pro Version
Commercial Support
Rendered Documentation
In-Browser Demos
Source Code
Issues and Bug Reports
Other General Support Issues
File format support for known spreadsheet data formats:
Graph of supported formats (click to show)
circo graph of format support
graph legend

Browser Test
Build Status
Build Status Build Status Coverage Status Dependencies Status npm Downloads Analytics

Table of Contents

Expand to show Table of Contents

JS Ecosystem Demos Optional Modules ECMAScript 5 Compatibility Parsing Examples Streaming Read Parsing and Writing Examples Writing Examples Streaming Write Parsing functions Writing functions Utilities General Structures Cell Object
+ [Data Types](#data-types)
+ [Dates](#dates)
Sheet Objects
+ [Worksheet Object](#worksheet-object)
+ [Chartsheet Object](#chartsheet-object)
+ [Macrosheet Object](#macrosheet-object)
+ [Dialogsheet Object](#dialogsheet-object)
Workbook Object
+ [Workbook File Properties](#workbook-file-properties)
Workbook-Level Attributes
+ [Defined Names](#defined-names)
+ [Miscellaneous Workbook Properties](#miscellaneous-workbook-properties)
Document Features
+ [Formulae](#formulae)
+ [Column Properties](#column-properties)
+ [Row Properties](#row-properties)
+ [Number Formats](#number-formats)
+ [Hyperlinks](#hyperlinks)
+ [Cell Comments](#cell-comments)
+ [Sheet Visibility](#sheet-visibility)
+ [VBA and Macros](#vba-and-macros)
Input Type Guessing File Type Supported Output Formats Output Type Array of Arrays Input Array of Objects Input HTML Table Input Formulae Output Delimiter-Separated Output
+ [UTF-16 Unicode Text](#utf-16-unicode-text)
HTML Output JSON Excel 2007+ XML (XLSX/XLSM) Excel 2.0-95 (BIFF2/BIFF3/BIFF4/BIFF5) Excel 97-2004 Binary (BIFF8) Excel 2003-2004 (SpreadsheetML) Excel 2007+ Binary (XLSB, BIFF12) Delimiter-Separated Values (CSV/TXT) Other Workbook Formats
+ [Lotus 1-2-3 (WKS/WK1/WK2/WK3/WK4/123)](#lotus-1-2-3-wkswk1wk2wk3wk4123)
+ [Quattro Pro (WQ1/WQ2/WB1/WB2/WB3/QPW)](#quattro-pro-wq1wq2wb1wb2wb3qpw)
+ [OpenDocument Spreadsheet (ODS/FODS)](#opendocument-spreadsheet-odsfods)
+ [Uniform Office Spreadsheet (UOS1/2)](#uniform-office-spreadsheet-uos12)
Other Single-Worksheet Formats
+ [dBASE and Visual FoxPro (DBF)](#dbase-and-visual-foxpro-dbf)
+ [Symbolic Link (SYLK)](#symbolic-link-sylk)
+ [Lotus Formatted Text (PRN)](#lotus-formatted-text-prn)
+ [Data Interchange Format (DIF)](#data-interchange-format-dif)
+ [HTML](#html)
+ [Rich Text Format (RTF)](#rich-text-format-rtf)
Node Browser Tested Environments Test Files OSX/Linux Windows Tests


In the browser, just add a script tag:
<script lang="javascript" src="dist/xlsx.full.min.js"></script>

CDN Availability (click to show)
| CDN | URL | |-----------:|:-----------------------------------------| | unpkg | | | jsDelivr | | | CDNjs | |
unpkg makes the latest version available at:
<script src=""></script>

With npm:
$ npm install xlsx

With bower:
$ bower install js-xlsx

JS Ecosystem Demos

The demos directory includes sample projects for:
Frameworks and APIs
Bundlers and Tooling
Platforms and Integrations

Optional Modules

Optional features (click to show)
The node version automatically requires modules for additional features. Some of these modules are rather large in size and are only needed in special circumstances, so they do not ship with the core. For browser use, they must be included directly:
<!-- international support from js-codepage -->
<script src="dist/cpexcel.js"></script>

An appropriate version for each dependency is included in the dist/ directory.
The complete single-file version is generated at dist/xlsx.full.min.js
Webpack and Browserify builds include optional modules by default. Webpack can be configured to remove support with resolve.alias:
/* uncomment the lines below to remove support */
resolve: {
  alias: { "./dist/cpexcel.js": "" } // <-- omit international support

ECMAScript 5 Compatibility

Since the library uses functions like Array#forEach, older browsers require shims to provide missing functions.
To use the shim, add the shim before the script tag that loads xlsx.js:
<!-- add the shim first -->
<script type="text/javascript" src="shim.js"></script>
<!-- after the shim is referenced, add the library -->
<script type="text/javascript" src="xlsx.full.min.js"></script>


Philosophy (click to show)
Prior to SheetJS, APIs for processing spreadsheet files were format-specific. Third-party libraries either supported one format, or they involved a separate set of classes for each supported file type. Even though XLSB was introduced in Excel 2007, nothing outside of SheetJS or Excel supported the format.
To promote a format-agnostic view, js-xlsx starts from a pure-JS representation that we call the "Common Spreadsheet Format". Emphasizing a uniform object representation enables new features like format conversion (reading an XLSX template and saving as XLS) and circumvents the "class trap". By abstracting the complexities of the various formats, tools need not worry about the specific file type!
A simple object representation combined with careful coding practices enables use cases in older browsers and in alternative environments like ExtendScript and Web Workers. It is always tempting to use the latest and greatest features, but they tend to require the latest versions of browsers, limiting usability.
Utility functions capture common use cases like generating JS objects or HTML. Most simple operations should only require a few lines of code. More complex operations generally should be straightforward to implement.
Excel pushes the XLSX format as default starting in Excel 2007. However, there are other formats with more appealing properties. For example, the XLSB format is spiritually similar to XLSX but files often tend up taking less than half the space and open much faster! Even though an XLSX writer is available, other format writers are available so users can take advantage of the unique characteristics of each format.

Parsing Workbooks

For parsing, the first step is to read the file. This involves acquiring the data and feeding it into the library. Here are a few common scenarios:
nodejs read a file (click to show)
readFile is only available in server environments. Browsers have no API for reading arbitrary files given a path, so another strategy must be used.
if(typeof require !== 'undefined') XLSX = require('xlsx');
var workbook = XLSX.readFile('test.xlsx');

Browser read TABLE element from page (click to show)
The table_to_book and table_to_sheet utility functions take a DOM TABLE element and iterate through the child nodes.
var worksheet = XLSX.utils.table_to_book(document.getElementById('tableau'));

Alternatively, the HTML code can be extracted and parsed:
var htmlstr = document.getElementById('tableau').outerHTML;
var worksheet =, {type:'string'});

Browser download file (ajax) (click to show)
Note: for a more complete example that works in older browsers, check the demo at ). The directory also includes more examples with XMLHttpRequest and fetch.
var url = "";

/* set up async GET request */
var req = new XMLHttpRequest();"GET", url, true);
req.responseType = "arraybuffer";

req.onload = function(e) {
  var data = new Uint8Array(req.response);
  var workbook =, {type:"array"});

  /* DO SOMETHING WITH workbook HERE */


Browser drag-and-drop (click to show)
Drag-and-drop uses the HTML5 FileReader API, loading the data with readAsBinaryString or readAsArrayBuffer. Since not all browsers support the full FileReader API, dynamic feature tests are highly recommended.
var rABS = true; // true: readAsBinaryString ; false: readAsArrayBuffer
function handleDrop(e) {
  e.stopPropagation(); e.preventDefault();
  var files = e.dataTransfer.files, f = files[0];
  var reader = new FileReader();
  reader.onload = function(e) {
    var data =;
    if(!rABS) data = new Uint8Array(data);
    var workbook =, {type: rABS ? 'binary' : 'array'});

    /* DO SOMETHING WITH workbook HERE */
  if(rABS) reader.readAsBinaryString(f); else reader.readAsArrayBuffer(f);
drop_dom_element.addEventListener('drop', handleDrop, false);

Browser file upload form element (click to show)
Data from file input elements can be processed using the same FileReader API as in the drag-and-drop example:
var rABS = true; // true: readAsBinaryString ; false: readAsArrayBuffer
function handleFile(e) {
  var files =, f = files[0];
  var reader = new FileReader();
  reader.onload = function(e) {
    var data =;
    if(!rABS) data = new Uint8Array(data);
    var workbook =, {type: rABS ? 'binary' : 'array'});

    /* DO SOMETHING WITH workbook HERE */
  if(rABS) reader.readAsBinaryString(f); else reader.readAsArrayBuffer(f);
input_dom_element.addEventListener('change', handleFile, false);

Parsing Examples

  • HTML5 File API / Base64 Text / Web Workers

Note that older versions of IE do not support HTML5 File API, so the Base64 mode is used for testing.
Get Base64 encoding on OSX / Windows (click to show)
On OSX you can get the Base64 encoding with:
$ <target_file base64 | pbcopy

On Windows XP and up you can get the Base64 encoding using certutil:
> certutil -encode target_file target_file.b64

(note: You have to open the file and remove the header and footer lines)

  • XMLHttpRequest

Streaming Read

Why is there no Streaming Read API? (click to show)
The most common and interesting formats (XLS, XLSX/M, XLSB, ODS) are ultimately ZIP or CFB containers of files. Neither format puts the directory structure at the beginning of the file: ZIP files place the Central Directory records at the end of the logical file, while CFB files can place the storage info anywhere in the file! As a result, to properly handle these formats, a streaming function would have to buffer the entire file before commencing. That belies the expectations of streaming, so we do not provide any streaming read API.

When dealing with Readable Streams, the easiest approach is to buffer the stream and process the whole thing at the end. This can be done with a temporary file or by explicitly concatenating the stream:
Explicitly concatenating streams (click to show)
var fs = require('fs');
var XLSX = require('xlsx');
function process_RS(stream/*:ReadStream*/, cb/*:(wb:Workbook)=>void*/)/*:void*/{
  var buffers = [];
  stream.on('data', function(data) { buffers.push(data); });
  stream.on('end', function() {
    var buffer = Buffer.concat(buffers);
    var workbook =, {type:"buffer"});


More robust solutions are available using modules like concat-stream.

Writing to filesystem first (click to show)
This example uses tempfile to generate file names:
var fs = require('fs'), tempfile = require('tempfile');
var XLSX = require('xlsx');
function process_RS(stream/*:ReadStream*/, cb/*:(wb:Workbook)=>void*/)/*:void*/{
  var fname = tempfile('.sheetjs');
  var ostream = fs.createWriteStream(fname);
  ostream.on('finish', function() {
    var workbook = XLSX.readFile(fname);


Working with the Workbook

The full object format is described later in this README.
Reading a specific cell (click to show)
This example extracts the value stored in cell A1 from the first worksheet:
var first_sheet_name = workbook.SheetNames[0];
var address_of_cell = 'A1';

/* Get worksheet */
var worksheet = workbook.Sheets[first_sheet_name];

/* Find desired cell */
var desired_cell = worksheet[address_of_cell];

/* Get the value */
var desired_value = (desired_cell ? desired_cell.v : undefined);

Adding a new worksheet to a workbook (click to show)
This example uses XLSX.utils.aoa_to_sheet to make a worksheet and appends the new worksheet to the workbook:
var new_ws_name = "SheetJS";

/* make worksheet */
var ws_data = [
  [ "S", "h", "e", "e", "t", "J", "S" ],
  [  1 ,  2 ,  3 ,  4 ,  5 ]
var ws = XLSX.utils.aoa_to_sheet(ws_data);

/* Add the sheet name to the list */

/* Load the worksheet object */
wb.Sheets[ws_name] = ws;

Parsing and Writing Examples

  • read + modify + write files

  • node

The node version installs a command line tool xlsx which can read spreadsheet files and output the contents in various formats. The source is available at xlsx.njs in the bin directory.
Some helper functions in XLSX.utils generate different views of the sheets:
  • XLSX.utils.sheet_to_csv generates CSV
  • XLSX.utils.sheet_to_html generates HTML
  • XLSX.utils.sheet_to_json generates an array of objects
  • XLSX.utils.sheet_to_formulae generates a list of formulae

Writing Workbooks

For writing, the first step is to generate output data. The helper functions write and writeFile will produce the data in various formats suitable for dissemination. The second step is to actual share the data with the end point. Assuming workbook is a workbook object:
nodejs write a file (click to show)
writeFile is only available in server environments. Browsers have no API for writing arbitrary files given a path, so another strategy must be used.
if(typeof require !== 'undefined') XLSX = require('xlsx');
/* output format determined by filename */
XLSX.writeFile(workbook, 'out.xlsb');
/* at this point, out.xlsb is a file that you can distribute */

Browser add to web page (click to show)
The sheet_to_html utility function generates HTML code that can be added to any DOM element.
var worksheet = workbook.Sheets[workbook.SheetNames[0]];
var container = document.getElementById('tableau');
container.innerHTML = XLSX.utils.sheet_to_html(worksheet);

Browser save file (click to show)
Note: browser generates binary blob and forces a "download" to client. This example uses FileSaver:
/* bookType can be any supported output type */
var wopts = { bookType:'xlsx', bookSST:false, type:'binary' };

var wbout = XLSX.write(workbook,wopts);

function s2ab(s) {
  var buf = new ArrayBuffer(s.length);
  var view = new Uint8Array(buf);
  for (var i=0; i!=s.length; ++i) view[i] = s.charCodeAt(i) & 0xFF;
  return buf;

/* the saveAs call downloads a file on the local machine */
saveAs(new Blob([s2ab(wbout)],{type:"application/octet-stream"}), "test.xlsx");

Browser upload to server (click to show)
A complete example using XHR is included in the XHR demo, along with examples for fetch and wrapper libraries. This example assumes the server can handle Base64-encoded files (see the demo for a basic nodejs server):
/* in this example, send a base64 string to the server */
var wopts = { bookType:'xlsx', bookSST:false, type:'base64' };

var wbout = XLSX.write(workbook,wopts);

var req = new XMLHttpRequest();"POST", "/upload", true);
var formdata = new FormData();
formdata.append('file', 'test.xlsx'); // <-- server expects `file` to hold name
formdata.append('data', wbout); // <-- `data` holds the base64-encoded data

Writing Examples

  • exporting an HTML table
  • generates a simple file

Streaming Write

The streaming write functions are available in the object. They take the same arguments as the normal write functions but return a Readable Stream. They are only exposed in NodeJS.
  • is the streaming version of XLSX.utils.sheet_to_csv.
  • is the streaming version of XLSX.utils.sheet_to_html.

nodejs convert to CSV and write file (click to show)
var output_file_name = "out.csv";
var stream =;

pipes write streams to nodejs response.


XLSX is the exposed variable in the browser and the exported node variable
XLSX.version is the version of the library (added by the build script).
XLSX.SSF is an embedded version of the format library.

Parsing functions, read_opts) attempts to parse data.
XLSX.readFile(filename, read_opts) attempts to read filename and parse.
Parse options are described in the Parsing Options section.

Writing functions

XLSX.write(wb, write_opts) attempts to write the workbook wb
XLSX.writeFile(wb, filename, write_opts) attempts to write wb to filename
XLSX.writeFileAsync(filename, wb, o, cb) attempts to write wb to filename. If o is omitted, the writer will use the third argument as the callback. contains a set of streaming write functions.
Write options are described in the Writing Options section.


Utilities are available in the XLSX.utils object and are described in the Utility Functions section:
  • aoa_to_sheet converts an array of arrays of JS data to a worksheet.
  • json_to_sheet converts an array of JS objects to a worksheet.
  • table_to_sheet converts a DOM TABLE element to a worksheet.

  • sheet_to_json converts a worksheet object to an array of JSON objects.
  • sheet_to_csv generates delimiter-separated-values output.
  • sheet_to_html generates HTML output.
  • sheet_to_formulae generates a list of the formulae (with value fallbacks).

Cell and cell address manipulation:
  • format_cell generates the text value for a cell (using number formats).
  • encode_row / decode_row converts between 0-indexed rows and 1-indexed rows.
  • encode_col / decode_col converts between 0-indexed columns and column names.
  • encode_cell / decode_cell converts cell addresses.
  • encode_range / decode_range converts cell ranges.

Common Spreadsheet Format

js-xlsx conforms to the Common Spreadsheet Format (CSF):

General Structures

Cell address objects are stored as {c:C, r:R} where C and R are 0-indexed column and row numbers, respectively. For example, the cell address B5 is represented by the object {c:1, r:4}.
Cell range objects are stored as {s:S, e:E} where S is the first cell and E is the last cell in the range. The ranges are inclusive. For example, the range A3:B7 is represented by the object {s:{c:0, r:2}, e:{c:1, r:6}}. Utility functions perform a row-major order walk traversal of a sheet range:
for(var R = range.s.r; R <= range.e.r; ++R) {
  for(var C = range.s.c; C <= range.e.c; ++C) {
    var cell_address = {c:C, r:R};
    /* if an A1-style address is needed, encode the address */
    var cell_ref = XLSX.utils.encode_cell(cell_address);

Cell Object

| Key | Description | | --- | ---------------------------------------------------------------------- | | v | raw value (see Data Types section for more info) | | w | formatted text (if applicable) | | t | cell type: b Boolean, n Number, e error, s String, d Date | | f | cell formula encoded as an A1-style string (if applicable) | | F | range of enclosing array if formula is array formula (if applicable) | | r | rich text encoding (if applicable) | | h | HTML rendering of the rich text (if applicable) | | c | comments associated with the cell | | z | number format string associated with the cell (if requested) | | l | cell hyperlink object (.Target holds link, .Tooltip is tooltip) | | s | the style/theme of the cell (if applicable) |
Built-in export utilities (such as the CSV exporter) will use the w text if it is available. To change a value, be sure to delete cell.w (or set it to undefined) before attempting to export. The utilities will regenerate the w text from the number format (cell.z) and the raw value if possible.
The actual array formula is stored in the f field of the first cell in the array range. Other cells in the range will omit the f field.

Data Types

The raw value is stored in the v field, interpreted based on the t field.
Type b is the Boolean type. v is interpreted according to JS truth tables.
Type e is the Error type. v holds the number and w holds the common name:
Error values and interpretation (click to show)
| Value | Error Meaning | | -----: | :-------------- | | 0x00 | #NULL! | | 0x07 | #DIV/0! | | 0x0F | #VALUE! | | 0x17 | #REF! | | 0x1D | #NAME? | | 0x24 | #NUM! | | 0x2A | #N/A | | 0x2B | #GETTING_DATA |

Type n is the Number type. This includes all forms of data that Excel stores as numbers, such as dates/times and Boolean fields. Excel exclusively uses data that can be fit in an IEEE754 floating point number, just like JS Number, so the v field holds the raw number. The w field holds formatted text. Dates are stored as numbers by default and converted with XLSX.SSF.parse_date_code.
Type d is the Date type, generated only when the option cellDates is passed. Since JSON does not have a natural Date type, parsers are generally expected to store ISO 8601 Date strings like you would get from date.toISOString(). On the other hand, writers and exporters should be able to handle date strings and JS Date objects. Note that Excel disregards timezone modifiers and treats all dates in the local timezone. js-xlsx does not correct for this error.
Type s is the String type. v should be explicitly stored as a string to avoid possible confusion.
Type z represents blank stub cells. These do not have any data or type, and are not processed by any of the core library functions. By default these cells will not be generated; the parser sheetStubs option must be set to true.


Excel Date Code details (click to show)
By default, Excel stores dates as numbers with a format code that specifies date processing. For example, the date 19-Feb-17 is stored as the number 42785 with a number format of d-mmm-yy. The SSF module understands number formats and performs the appropriate conversion.
XLSX also supports a special date type d where the data is an ISO 8601 date string. The formatter converts the date back to a number.
The default behavior for all parsers is to generate number cells. Setting cellDates to true will force the generators to store dates.

Time Zones and Dates (click to show)
Excel has no native concept of universal time. All times are specified in the local time zone. Excel limitations prevent specifying true absolute dates.
Following Excel, this library treats all dates as relative to local time zone.

Epochs: 1900 and 1904 (click to show)
Excel supports two epochs (January 1 1900 and January 1 1904), see "1900 vs. 1904 Date System" article. The workbook's epoch can be determined by examining the workbook's wb.Workbook.WBProps.date1904 property:

Sheet Objects

Each key that does not start with ! maps to a cell (using A-1 notation)
sheet[address] returns the cell object for the specified address.
Special sheet keys (accessible as sheet[key], each starting with !):
  • sheet['!ref']: A-1 based range representing the sheet range. Functions that
work with sheets should use this parameter to determine the range. Cells that are assigned outside of the range are not processed. In particular, when writing a sheet by hand, cells outside of the range are not included
Functions that handle sheets should test for the presence of !ref field. If the !ref is omitted or is not a valid range, functions are free to treat the sheet as empty or attempt to guess the range. The standard utilities that ship with this library treat sheets as empty (for example, the CSV output is empty string).
When reading a worksheet with the sheetRows property set, the ref parameter will use the restricted range. The original range is set at ws['!fullref']
  • sheet['!margins']: Object representing the page margins. The default values
follow Excel's "normal" preset. Excel also has a "wide" and a "narrow" preset but they are stored as raw measurements. The main properties are listed below:
Page margin details (click to show)
| key | description | "normal" | "wide" | "narrow" | |----------|------------------------|:---------|:-------|:-------- | | left | left margin (inches) | 0.7 | 1.0 | 0.25 | | right | right margin (inches) | 0.7 | 1.0 | 0.25 | | top | top margin (inches) | 0.75 | 1.0 | 0.75 | | bottom | bottom margin (inches) | 0.75 | 1.0 | 0.75 | | header | header margin (inches) | 0.3 | 0.5 | 0.3 | | footer | footer margin (inches) | 0.3 | 0.5 | 0.3 |
/* Set worksheet sheet to "normal" */
ws["!margins"]={left:0.7, right:0.7, top:0.75,bottom:0.75,header:0.3,footer:0.3}
/* Set worksheet sheet to "wide" */
ws["!margins"]={left:1.0, right:1.0, top:1.0, bottom:1.0, header:0.5,footer:0.5}
/* Set worksheet sheet to "narrow" */

Worksheet Object

In addition to the base sheet keys, worksheets also add:
  • ws['!cols']: array of column properties objects. Column widths are actually
stored in files in a normalized manner, measured in terms of the "Maximum Digit Width" (the largest width of the rendered digits 0-9, in pixels). When parsed, the column objects store the pixel width in the wpx field, character width in the wch field, and the maximum digit width in the MDW field.
  • ws['!rows']: array of row properties objects as explained later in the docs.
Each row object encodes properties including row height and visibility.
  • ws['!merges']: array of range objects corresponding to the merged cells in
the worksheet. Plain text formats do not support merge cells. CSV export will write all cells in the merge range if they exist, so be sure that only the first cell (upper-left) in the range is set.
  • ws['!protect']: object of write sheet protection properties. The password
key specifies the password for formats that support password-protected sheets (XLSX/XLSB/XLS). The writer uses the XOR obfuscation method. The following keys control the sheet protection -- set to false to enable a feature when sheet is locked or set to true to disable a feature:
Worksheet Protection Details (click to show)
| key | feature (true=disabled / false=enabled) | default | |:----------------------|:----------------------------------------|:-----------| | selectLockedCells | Select locked cells | enabled | | selectUnlockedCells | Select unlocked cells | enabled | | formatCells | Format cells | disabled | | formatColumns | Format columns | disabled | | formatRows | Format rows | disabled | | insertColumns | Insert columns | disabled | | insertRows | Insert rows | disabled | | insertHyperlinks | Insert hyperlinks | disabled | | deleteColumns | Delete columns | disabled | | deleteRows | Delete rows | disabled | | sort | Sort | disabled | | autoFilter | Filter | disabled | | pivotTables | Use PivotTable reports | disabled | | objects | Edit objects | enabled | | scenarios | Edit scenarios | enabled |
  • ws['!autofilter']: AutoFilter object following the schema:

type AutoFilter = {
  ref:string; // A-1 based range representing the AutoFilter table range

Chartsheet Object

Chartsheets are represented as standard sheets. They are distinguished with the !type property set to "chart".
The underlying data and !ref refer to the cached data in the chartsheet. The first row of the chartsheet is the underlying header.

Macrosheet Object

Macrosheets are represented as standard sheets. They are distinguished with the !type property set to "macro".

Dialogsheet Object

Dialogsheets are represented as standard sheets. They are distinguished with the !type property set to "dialog".

Workbook Object

workbook.SheetNames is an ordered list of the sheets in the workbook
wb.Sheets[sheetname] returns an object representing the worksheet.
wb.Props is an object storing the standard properties. wb.Custprops stores custom properties. Since the XLS standard properties deviate from the XLSX standard, XLS parsing stores core properties in both places.
wb.Workbook stores workbook-level attributes.

Workbook File Properties

The various file formats use different internal names for file properties. The workbook Props object normalizes the names:
File Properties (click to show)
| JS Name | Excel Description | |:--------------|:-------------------------------| | Title | Summary tab "Title" | | Subject | Summary tab "Subject" | | Author | Summary tab "Author" | | Manager | Summary tab "Manager" | | Company | Summary tab "Company" | | Category | Summary tab "Category" | | Keywords | Summary tab "Keywords" | | Comments | Summary tab "Comments" | | LastAuthor | Statistics tab "Last saved by" | | CreatedDate | Statistics tab "Created" |

For example, to set the workbook title property:
if(!wb.Props) wb.Props = {};
wb.Props.Title = "Insert Title Here";

Custom properties are added in the workbook Custprops object:
if(!wb.Custprops) wb.Custprops = {};
wb.Custprops["Custom Property"] = "Custom Value";

Writers will process the Props key of the options object:
/* force the Author to be "SheetJS" */
XLSX.write(wb, {Props:{Author:"SheetJS"}});

Workbook-Level Attributes

wb.Workbook stores workbook-level attributes.

Defined Names

wb.Workbook.Names is an array of defined name objects which have the keys:
Defined Name Properties (click to show)
| Key | Description | |:----------|:-----------------------------------------------------------------| | Sheet | Name scope. Sheet Index (0 = first sheet) or null (Workbook) | | Name | Case-sensitive name. Standard rules apply | | Ref | A1-style Reference ("Sheet1!$A$1:$D$20") | | Comment | Comment (only applicable for XLS/XLSX/XLSB) |

Excel allows two sheet-scoped defined names to share the same name. However, a sheet-scoped name cannot collide with a workbook-scope name. Workbook writers may not enforce this constraint.

Miscellaneous Workbook Properties

wb.Workbook.WBProps holds other workbook properties:
| Key | Description | |:----------------|:----------------------------------------------------| | date1904 | epoch: 0/false for 1900 system, 1/true for 1904 | | filterPrivacy | Warn or strip personally identifying info on save |

Document Features

Even for basic features like date storage, the official Excel formats store the same content in different ways. The parsers are expected to convert from the underlying file format representation to the Common Spreadsheet Format. Writers are expected to convert from CSF back to the underlying file format.


The A1-style formula string is stored in the f field. Even though different file formats store the formulae in different ways, the formats are translated. Even though some formats store formulae with a leading equal sign, CSF formulae do not start with =.
Representation of A1=1, A2=2, A3=A1+A2 (click to show)
  "!ref": "A1:A3",
  A1: { t:'n', v:1 },
  A2: { t:'n', v:2 },
  A3: { t:'n', v:3, f:'A1+A2' }

Shared formulae are decompressed and each cell has the formula corresponding to its cell. Writers generally do not attempt to generate shared formulae.
Cells with formula entries but no value will be serialized in a way that Excel and other spreadsheet tools will recognize. This library will not automatically compute formula results! For example, to compute BESSELJ in a worksheet:
Formula without known value (click to show)
  "!ref": "A1:A3",
  A1: { t:'n', v:3.14159 },
  A2: { t:'n', v:2 },
  A3: { t:'n', f:'BESSELJ(A1,A2)' }

Array Formulae
Array formulae are stored in the top-left cell of the array block. All cells of an array formula have a F field corresponding to the range. A single-cell formula can be distinguished from a plain formula by the presence of F field.
Array Formula examples (click to show)
For example, setting the cell C1 to the array formula {=SUM(A1:A3*B1:B3)}:
worksheet['C1'] = { t:'n', f: "SUM(A1:A3*B1:B3)", F:"C1:C1" };

For a multi-cell array formula, every cell has the same array range but only the first cell specifies the formula. Consider D1:D3=A1:A3*B1:B3:
worksheet['D1'] = { t:'n', F:"D1:D3", f:"A1:A3*B1:B3" };
worksheet['D2'] = { t:'n', F:"D1:D3" };
worksheet['D3'] = { t:'n', F:"D1:D3" };

Utilities and writers are expected to check for the presence of a F field and ignore any possible formula element f in cells other than the starting cell. They are not expected to perform validation of the formulae!
Formula Output Utility Function (click to show)
The sheet_to_formulae method generates one line per formula or array formula. Array formulae are rendered in the form range=formula while plain cells are rendered in the form cell=formula or value. Note that string literals are prefixed with an apostrophe ', consistent with Excel's formula bar display.
Formulae File Format Details (click to show)
| Storage Representation | Formats | Read | Write | |:-----------------------|:-------------------------|:-----:|:-----:| | A1-style strings | XLSX | :o: | :o: | | RC-style strings | XLML and plain text | :o: | :o: | | BIFF Parsed formulae | XLSB and all XLS formats | :o: | | | OpenFormula formulae | ODS/FODS/UOS | :o: | :o: |
Since Excel prohibits named cells from colliding with names of A1 or RC style cell references, a (not-so-simple) regex conversion is possible. BIFF Parsed formulae have to be explicitly unwound. OpenFormula formulae can be converted with regular expressions.

Column Properties

The !cols array in each worksheet, if present, is a collection of ColInfo objects which have the following properties:
type ColInfo = {
  /* visibility */
  hidden?: boolean; // if true, the column is hidden

  /* column width is specified in one of the following ways: */
  wpx?:    number;  // width in screen pixels
  width?:  number;  // width in Excel's "Max Digit Width", width*256 is integral
  wch?:    number;  // width in characters

  /* other fields for preserving features from files */
  MDW?:    number;  // Excel's "Max Digit Width" unit, always integral

Why are there three width types? (click to show)
There are three different width types corresponding to the three different ways spreadsheets store column widths:
SYLK and other plain text formats use raw character count. Contemporaneous tools like Visicalc and Multiplan were character based. Since the characters had the same width, it sufficed to store a count. This tradition was continued into the BIFF formats.
SpreadsheetML (2003) tried to align with HTML by standardizing on screen pixel count throughout the file. Column widths, row heights, and other measures use pixels. When the pixel and character counts do not align, Excel rounds values.
XLSX internally stores column widths in a nebulous "Max Digit Width" form. The Max Digit Width is the width of the largest digit when rendered (generally the "0" character is the widest). The internal width must be an integer multiple of the the width divided by 256. ECMA-376 describes a formula for converting between pixels and the internal width. This represents a hybrid approach.
Read functions attempt to populate all three properties. Write functions will try to cycle specified values to the desired type. In order to avoid potential conflicts, manipulation should delete the other properties first. For example, when changing the pixel width, delete the wch and width properties.
Implementation details (click to show)
Given the constraints, it is possible to determine the MDW without actually inspecting the font! The parsers guess the pixel width by converting from width to pixels and back, repeating for all possible MDW and selecting the MDW that minimizes the error. XLML actually stores the pixel width, so the guess works in the opposite direction.
Even though all of the information is made available, writers are expected to follow the priority order:
1) use width field if available 2) use wpx pixel width if available 3) use wch character count if available

Row Properties

The !rows array in each worksheet, if present, is a collection of RowInfo objects which have the following properties:
type RowInfo = {
  /* visibility */
  hidden?: boolean; // if true, the row is hidden

  /* row height is specified in one of the following ways: */
  hpx?:    number;  // height in screen pixels
  hpt?:    number;  // height in points

  level?:  number;  // 0-indexed outline / group level

Note: Excel UI displays the base outline level as 1 and the max level as 8. The level field stores the base outline as 0 and the max level as 7.
Implementation details (click to show)
Excel internally stores row heights in points. The default resolution is 72 DPI or 96 PPI, so the pixel and point size should agree. For different resolutions they may not agree, so the library separates the concepts.
Even though all of the information is made available, writers are expected to follow the priority order:
1) use hpx pixel height if available 2) use hpt point height if available

Number Formats

The cell.w formatted text for each cell is produced from cell.v and cell.z format. If the format is not specified, the Excel General format is used. The format can either be specified as a string or as an index into the format table. Parsers are expected to populate workbook.SSF with the number format table. Writers are expected to serialize the table.
Custom tools should ensure that the local table has each used format string somewhere in the table. Excel convention mandates that the custom formats start at index 164. The following example creates a custom format from scratch:
New worksheet with custom format (click to show)
var wb = {
  SheetNames: ["Sheet1"],
  Sheets: {
    Sheet1: {
      A1: { t:"n", v:10000 },                    // <-- General format
      B1: { t:"n", v:10000, z: "0%" },           // <-- Builtin format
      C1: { t:"n", v:10000, z: "\"T\"\ #0.00" }  // <-- Custom format

The rules are slightly different from how Excel displays custom number formats. In particular, literal characters must be wrapped in double quotes or preceded by a backslash. For more info, see the Excel documentation article Create or delete a custom number format or ECMA-376 18.8.31 (Number Formats)
Default Number Formats (click to show)
The default formats are listed in ECMA-376 18.8.30:
| ID | Format | |---:|:---------------------------| | 0 | General | | 1 | 0 | | 2 | 0.00 | | 3 | #,##0 | | 4 | #,##0.00 | | 9 | 0% | | 10 | 0.00% | | 11 | 0.00E+00 | | 12 | # ?/? | | 13 | # ??/?? | | 14 | m/d/yy (see below) | | 15 | d-mmm-yy | | 16 | d-mmm | | 17 | mmm-yy | | 18 | h:mm AM/PM | | 19 | h:mm:ss AM/PM | | 20 | h:mm | | 21 | h:mm:ss | | 22 | m/d/yy h:mm | | 37 | #,##0 ;(#,##0) | | 38 | #,##0 ;[Red](#,##0) | | 39 | #,##0.00;(#,##0.00) | | 40 | #,##0.00;[Red](#,##0.00) | | 45 | mm:ss | | 46 | [h]:mm:ss | | 47 | mmss.0 | | 48 | ##0.0E+0 | | 49 | @ |

Format 14 (m/d/yy) is localized by Excel: even though the file specifies that number format, it will be drawn differently based on system settings. It makes sense when the producer and consumer of files are in the same locale, but that is not always the case over the Internet. To get around this ambiguity, parse functions accept the dateNF option to override the interpretation of that specific format string.


Hyperlinks are stored in the l key of cell objects. The Target field of the hyperlink object is the target of the link, including the URI fragment. Tooltips are stored in the Tooltip field and are displayed when you move your mouse over the text.
For example, the following snippet creates a link from cell A3 to with the tip "Find us @!":
ws['A3'].l = { Target:"", Tooltip:"Find us @!" };

Note that Excel does not automatically style hyperlinks -- they will generally be displayed as normal text.

Cell Comments

Cell comments are objects stored in the c array of cell objects. The actual contents of the comment are split into blocks based on the comment author. The a field of each comment object is the author of the comment and the t field is the plain text representation.
For example, the following snippet appends a cell comment into cell A1:
if(!ws.A1.c) ws.A1.c = [];
ws.A1.c.push({a:"SheetJS", t:"I'm a little comment, short and stout!"});

Note: XLSB enforces a 54 character limit on the Author name. Names longer than 54 characters may cause issues with other formats.

Sheet Visibility

Excel enables hiding sheets in the lower tab bar. The sheet data is stored in the file but the UI does not readily make it available. Standard hidden sheets are revealed in the "Unhide" menu. Excel also has "very hidden" sheets which cannot be revealed in the menu. It is only accessible in the VB Editor!
The visibility setting is stored in the Hidden property of sheet props array.
More details (click to show)
| Value | Definition | |:-----:|:------------| | 0 | Visible | | 1 | Hidden | | 2 | Very Hidden |
With files/master/sheetvisibility.xlsx>:
> { return [, x.Hidden] })
[ [ 'Visible', 0 ], [ 'Hidden', 1 ], [ 'VeryHidden', 2 ] ]

Non-Excel formats do not support the Very Hidden state. The best way to test if a sheet is visible is to check if the Hidden property is logical truth:
> { return [, !x.Hidden] })
[ [ 'Visible', true ], [ 'Hidden', false ], [ 'VeryHidden', false ] ]

VBA and Macros

VBA Macros are stored in a special data blob that is exposed in the vbaraw property of the workbook object when the bookVBA option is true. They are supported in XLSM, XLSB, and BIFF8 XLS formats. The supported format writers automatically insert the data blobs if it is present in the workbook and associate with the worksheet names.
<summary><b>Macrosheets</b> (click to show)</summary>
Older versions of Excel also supported a non-VBA "macrosheet" sheet type that stored automation commands. These are exposed in objects with the !type property set to "macro".

<summary><b>Detecting macros in workbooks</b> (click to show)</summary>
The vbaraw field will only be set if macros are present, so testing is simple:
function wb_has_macro(wb/*:workbook*/)/*:boolean*/ {
	if(!!wb.vbaraw) return true;
	const sheets = => wb.Sheets[n]);
	return sheets.some((ws) => !!ws && ws['!type']=='macro');

Parsing Options

The exported read and readFile functions accept an options argument:
| Option Name | Default | Description | | :---------- | ------: | :--------------------------------------------------- | |type | | Input data encoding (see Input Type below) | |raw | false | If true, plain text parsing will not parse values
| |cellFormula| true | Save formulae to the .f field | |cellHTML | true | Parse rich text and save HTML to the .h field | |cellNF | false | Save number format string to the .z field | |cellStyles | false | Save style/theme info to the .s field | |cellText | true | Generated formatted text to the .w field | |cellDates | false | Store dates as type d (default is n) | |dateNF | | If specified, use the string for date code 14 | |sheetStubs | false | Create cell objects of type z for stub cells | |sheetRows | 0 | If >0, read the first sheetRows rows | |bookDeps | false | If true, parse calculation chains | |bookFiles | false | If true, add raw files to book object | |bookProps | false | If true, only parse enough to get book metadata | |bookSheets | false | If true, only parse enough to get the sheet names | |bookVBA | false | If true, copy VBA blob to vbaraw field | |password | "" | If defined and file is encrypted, use password | |WTF | false | If true, throw errors on unexpected file features |
  • Even if cellNF is false, formatted text will be generated and saved to .w
  • In some cases, sheets may be parsed even if bookSheets is false.
  • Excel aggressively tries to interpret values from CSV and other plain text.
This leads to surprising behavior! The raw option suppresses value parsing.
  • bookSheets and bookProps combine to give both sets of information
  • Deps will be an empty object if bookDeps is false
  • bookFiles behavior depends on file type:
* `keys` array (paths in the ZIP) for ZIP-based formats
* `files` hash (mapping paths to objects representing the files) for ZIP
* `cfb` object for formats using CFB containers
  • sheetRows-1 rows will be generated when looking at the JSON object output
(since the header row is counted as a row when parsing the data)
  • bookVBA merely exposes the raw VBA CFB object. It does not parse the data.
XLSM and XLSB store the VBA CFB object in xl/vbaProject.bin. BIFF8 XLS mixes the VBA entries alongside the core Workbook entry, so the library generates a new XLSB-compatible blob from the XLS CFB container.
  • Currently only XOR encryption is supported. Unsupported error will be thrown
for files employing other encryption methods.
  • WTF is mainly for development. By default, the parser will suppress read
errors on single worksheets, allowing you to read from the worksheets that do parse properly. Setting WTF:1 forces those errors to be thrown.

Input Type

Strings can be interpreted in multiple ways. The type parameter for read tells the library how to parse the data argument:
| type | expected input | |------------|-----------------------------------------------------------------| | "base64" | string: Base64 encoding of the file | | "binary" | string: binary string (byte n is data.charCodeAt(n)) | | "string" | string: JS string (characters interpreted as UTF8) | | "buffer" | nodejs Buffer | | "array" | array: array of 8-bit unsigned int (byte n is data[n]) | | "file" | string: path of file that will be read (nodejs only) |

Guessing File Type

Implementation Details (click to show)
Excel and other spreadsheet tools read the first few bytes and apply other heuristics to determine a file type. This enables file type punning: renaming files with the .xls extension will tell your computer to use Excel to open the file but Excel will know how to handle it. This library applies similar logic:
| Byte 0 | Raw File Type | Spreadsheet Types | |:-------|:--------------|:----------------------------------------------------| | 0xD0 | CFB Container | BIFF 5/8 or password-protected XLSX/XLSB or WQ3/QPW | | 0x09 | BIFF Stream | BIFF 2/3/4/5 | | 0x3C | XML/HTML | SpreadsheetML / Flat ODS / UOS1 / HTML / plain text | | 0x50 | ZIP Archive | XLSB or XLSX/M or ODS or UOS2 or plain text | | 0x49 | Plain Text | SYLK or plain text | | 0x54 | Plain Text | DIF or plain text | | 0xEF | UTF8 Encoded | SpreadsheetML / Flat ODS / UOS1 / HTML / plain text | | 0xFF | UTF16 Encoded | SpreadsheetML / Flat ODS / UOS1 / HTML / plain text | | 0x00 | Record Stream | Lotus WK\* or Quattro Pro or plain text | | 0x7B | Plain text | RTF or plain text | | 0x0A | Plain text | SpreadsheetML / Flat ODS / UOS1 / HTML / plain text | | 0x0D | Plain text | SpreadsheetML / Flat ODS / UOS1 / HTML / plain text | | 0x20 | Plain text | SpreadsheetML / Flat ODS / UOS1 / HTML / plain text |
DBF files are detected based on the first byte as well as the third and fourth bytes (corresponding to month and day of the file date)
Plain text format guessing follows the priority order:
| Format | Test | |:-------|:--------------------------------------------------------------------| | XML | <?xml appears in the first 1024 characters | | HTML | starts with < and HTML tags appear in the first 1024 characters | | XML | starts with < | | RTF | starts with {\rt | | DSV | starts with /sep=.$/, separator is the specified character | | DSV | more unquoted ";" chars than "\t" or "," in the first 1024 | | TSV | more unquoted "\t" chars than "," chars in the first 1024 | | CSV | one of the first 1024 characters is a comma "," | | PRN | (default) |
  • HTML tags include: html, table, head, meta, script, style, div

Why are random text files valid? (click to show)
Excel is extremely aggressive in reading files. Adding an XLS extension to any display text file (where the only characters are ANSI display chars) tricks Excel into thinking that the file is potentially a CSV or TSV file, even if it is only one column! This library attempts to replicate that behavior.
The best approach is to validate the desired worksheet and ensure it has the expected number of rows or columns. Extracting the range is extremely simple:
var range = XLSX.utils.decode_range(worksheet['!ref']);
var ncols = range.e.c - range.r.c + 1, nrows = range.e.r - range.s.r + 1;

Writing Options

The exported write and writeFile functions accept an options argument:
| Option Name | Default | Description | | :---------- | -------: | :-------------------------------------------------- | |type | | Output data encoding (see Output Type below) | |cellDates | false | Store dates as type d (default is n) | |bookSST | false | Generate Shared String Table | |bookType | "xlsx" | Type of Workbook (see below for supported formats) | |sheet | "" | Name of Worksheet for single-sheet formats | |compression| false | Use ZIP compression for ZIP-based formats | |Props | | Override workbook properties when writing | |themeXLSX | | Override theme XML when writing XLSX/XLSB/XLSM |
  • bookSST is slower and more memory intensive, but has better compatibility
with older versions of iOS Numbers
  • The raw data is the only thing guaranteed to be saved. Features not described
in this README may not be serialized.
  • cellDates only applies to XLSX output and is not guaranteed to work with
third-party readers. Excel itself does not usually write cells with type d so non-Excel tools may ignore the data or error in the presence of dates.
  • Props is an object mirroring the workbook Props field. See the table from
the Workbook File Properties
  • if specified, the string from themeXLSX will be saved as the primary theme
for XLSX/XLSB/XLSM files (to xl/theme/theme1.xml in the ZIP)

Supported Output Formats

For broad compatibility with third-party tools, this library supports many output formats. The specific file type is controlled with bookType option:
| bookType | file ext | container | sheets | Description | | :--------- | -------: | :-------: | :----- |:------------------------------- | | xlsx | .xlsx | ZIP | multi | Excel 2007+ XML Format | | xlsm | .xlsm | ZIP | multi | Excel 2007+ Macro XML Format | | xlsb | .xlsb | ZIP | multi | Excel 2007+ Binary Format | | biff8 | .xls | CFB | multi | Excel 97-2004 Workbook Format | | biff5 | .xls | CFB | multi | Excel 5.0/95 Workbook Format | | biff2 | .xls | none | single | Excel 2.0 Worksheet Format | | xlml | .xls | none | multi | Excel 2003-2004 (SpreadsheetML) | | ods | .ods | ZIP | multi | OpenDocument Spreadsheet | | fods | .fods | none | multi | Flat OpenDocument Spreadsheet | | csv | .csv | none | single | Comma Separated Values | | txt | .txt | none | single | UTF-16 Unicode Text (TXT) | | sylk | .sylk | none | single | Symbolic Link (SYLK) | | html | .html | none | single | HTML Document | | dif | .dif | none | single | Data Interchange Format (DIF) | | dbf | .dbf | none | single | dBASE II + VFP Extensions (DBF) | | rtf | .rtf | none | single | Rich Text Format (RTF) | | prn | .prn | none | single | Lotus Formatted Text |
  • compression only applies to formats with ZIP containers.
  • Formats that only support a single sheet require a sheet option specifying
the worksheet. If the string is empty, the first worksheet is used.
  • writeFile will automatically guess the output file format based on the file
extension if bookType is not specified. It will choose the first format in the aforementioned table that matches the extension.

Output Type

The type argument for write mirrors the type argument for read:
| type | output | |------------|-----------------------------------------------------------------| | "base64" | string: Base64 encoding of the file | | "binary" | string: binary string (byte n is data.charCodeAt(n)) | | "string" | string: JS string (characters interpreted as UTF8) | | "buffer" | nodejs Buffer | | "file" | string: path of file that will be created (nodejs only) |

Utility Functions

The sheet_to_* functions accept a worksheet and an optional options object.
The *_to_sheet functions accept a data object and an optional options object.
The examples are based on the following worksheet:
XXX| A | B | C | D | E | F | G |
 1 | S | h | e | e | t | J | S |
 2 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
 3 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |

Array of Arrays Input

XLSX.utils.aoa_to_sheet takes an array of arrays of JS values and returns a worksheet resembling the input data. Numbers, Booleans and Strings are stored as the corresponding styles. Dates are stored as date or numbers. Array holes and explicit undefined values are skipped. null v