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xlsx v0.9.6

Excel (XLSB/XLSX/XLSM/XLS/XML) and ODS (ODS/FODS/UOS) spreadsheet parser and writer


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.

In-Browser Demo

Source Code

Commercial Support

File format support for known spreadsheet data formats:

circo graph of format support

Table of Contents


With npm:

$ npm install xlsx

In the browser:

<script lang="javascript" src="dist/xlsx.core.min.js"></script>

With bower:

$ bower install js-xlsx

CDNjs automatically pulls the latest version and makes all versions available at

JS Ecosystem Demos

The demos directory includes sample projects for:

Optional Modules

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 xlsx.js uses ES5 functions like Array#forEach, older browsers require Polyfills. This repo and the gh-pages branch include a shim

To use the shim, add the shim before the script tag that loads xlsx.js:

<script type="text/javascript" src="/path/to/shim.js"></script>

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:

  • node readFile:
if(typeof require !== 'undefined') XLSX = require('xlsx');
var workbook = XLSX.readFile('test.xlsx');
/* set up XMLHttpRequest */
var url = "test_files/formula_stress_test_ajax.xlsx";
var oReq = new XMLHttpRequest();"GET", url, true);
oReq.responseType = "arraybuffer";

oReq.onload = function(e) {
  var arraybuffer = oReq.response;

  /* convert data to binary string */
  var data = new Uint8Array(arraybuffer);
  var arr = new Array();
  for(var i = 0; i != data.length; ++i) arr[i] = String.fromCharCode(data[i]);
  var bstr = arr.join("");

  /* Call XLSX */
  var workbook =, {type:"binary"});

  /* DO SOMETHING WITH workbook HERE */

  • HTML5 drag-and-drop using readAsBinaryString or readAsArrayBuffer: note: readAsBinaryString and readAsArrayBuffer may not be available in every browser. Use dynamic feature tests to determine which method to use.
/* processing array buffers, only required for readAsArrayBuffer */
function fixdata(data) {
  var o = "", l = 0, w = 10240;
  for(; l<data.byteLength/w; ++l) o+=String.fromCharCode.apply(null,new Uint8Array(data.slice(l*w,l*w+w)));
  o+=String.fromCharCode.apply(null, new Uint8Array(data.slice(l*w)));
  return o;

var rABS = true; // true: readAsBinaryString ; false: readAsArrayBuffer
/* set up drag-and-drop event */
function handleDrop(e) {
  var files = e.dataTransfer.files;
  var i,f;
  for (i = 0; i != files.length; ++i) {
    f = files[i];
    var reader = new FileReader();
    var name =;
    reader.onload = function(e) {
      var data =;

      var workbook;
      if(rABS) {
        /* if binary string, read with type 'binary' */
        workbook =, {type: 'binary'});
      } else {
        /* if array buffer, convert to base64 */
        var arr = fixdata(data);
        workbook =, {type: 'base64'});

      /* DO SOMETHING WITH workbook HERE */
    if(rABS) reader.readAsBinaryString(f);
    else reader.readAsArrayBuffer(f);
drop_dom_element.addEventListener('drop', handleDrop, false);
  • HTML5 input file element using readAsBinaryString or readAsArrayBuffer:
/* fixdata and rABS are defined in the drag and drop example */
function handleFile(e) {
  var files =;
  var i,f;
  for (i = 0; i != files.length; ++i) {
    f = files[i];
    var reader = new FileReader();
    var name =;
    reader.onload = function(e) {
      var data =;

      var workbook;
      if(rABS) {
        /* if binary string, read with type 'binary' */
        workbook =, {type: 'binary'});
      } else {
        /* if array buffer, convert to base64 */
        var arr = fixdata(data);
        workbook =, {type: 'base64'});

      /* DO SOMETHING WITH workbook HERE */
input_dom_element.addEventListener('change', handleFile, false);

Working with the Workbook

The full object format is described later in this README.

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);

Complete examples:

Note that older versions of IE do not support HTML5 File API, so the base64 mode is used for testing. 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)

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_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 to file:
/* output format determined by filename */
XLSX.writeFile(workbook, 'out.xlsx');
/* at this point, out.xlsx is a file that you can distribute */
  • browser generate binary blob and "download" to client (using FileSaver.js for download):
/* bookType can be 'xlsx' or 'xlsm' or 'xlsb' or 'ods' */
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");

Complete examples:


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.

Write options are described in the Writing Options section.


Utilities are available in the XLSX.utils object:


  • aoa_to_sheet converts an array of arrays of JS data to a worksheet.


  • sheet_to_json converts a worksheet object to an array of JSON objects. sheet_to_row_object_array is an alias that will be removed in the future.
  • sheet_to_csv generates delimiter-separated-values output.
  • sheet_to_formulae generates a list of the formulae (with value fallbacks).

Exporters are described in the Utility Functions section.

Cell and cell address manipulation:

  • format_cell generates the text value for a cell (using number formats)
  • {en,de}code_{row,col} convert between 0-indexed rows/cols and A1 forms.
  • {en,de}code_cell converts cell addresses
  • {en,de}code_range converts cell ranges

Workbook / Worksheet / Cell Object Description

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}}. Utils use the following pattern to walk each of the cells in a 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};

Cell Object

vraw value (see Data Types section for more info)
wformatted text (if applicable)
tcell type: b Boolean, n Number, e error, s String, d Date
fcell formula encoded as an A1-style string (if applicable)
Frange of enclosing array if formula is array formula (if applicable)
rrich text encoding (if applicable)
hHTML rendering of the rich text (if applicable)
ccomments associated with the cell
znumber format string associated with the cell (if requested)
lcell hyperlink object (.Target holds link, .tooltip is tooltip)
sthe 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:

ValueError Meaning

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.


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.

Worksheet Object

Each key that does not start with ! maps to a cell (using A-1 notation)

worksheet[address] returns the cell object for the specified address.

Special worksheet keys (accessible as worksheet[key], each starting with !):

  • ws['!ref']: A-1 based range representing the worksheet 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 worksheet by hand, be sure to update the range. For a longer discussion, see

    Functions that handle worksheets 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']

  • 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['!merges']: array of range objects corresponding to the merged cells in the worksheet. Plaintext utilities are unaware of 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.

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.WBProps includes more workbook-level properties:

  • Excel supports two epochs (January 1 1900 and January 1 1904), see 1900 vs. 1904 Date System. The workbook's epoch can be determined by examining the workbook's wb.WBProps.date1904 property.

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 =.

The worksheet representation of A1=1, A2=2, A3=A1+A2:

    "!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:

    "!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.

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 has content. 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

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

Storage RepresentationFormatsReadWrite
A1-style stringsXLSX:o::o:
RC-style stringsXLML and plaintext:o::o:
BIFF Parsed formulaeXLSB and all XLS formats:o:
OpenFormula formulaeODS/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 regexes for the most part.

Column Properties

Excel internally stores column widths in a nebulous "Max Digit Width" form. The Max Digit Width is the width of the largest digit when rendered. 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.

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.

The !cols array in each worksheet, if present, is a collection of ColInfo objects which have the following properties:

type ColInfo = {
    MDW?:number;  // Excel's "Max Digit Width" unit, always integral
    width:number; // width in Excel's "Max Digit Width", width*256 is integral
    wpx?:number;  // width in screen pixels
    wch?:number;  // intermediate character calculation

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

Parsing Options

The exported read and readFile functions accept an options argument:

Option NameDefaultDescription
typeInput data encoding (see Input Type below)
cellFormulatrueSave formulae to the .f field
cellHTMLtrueParse rich text and save HTML to the .h field
cellNFfalseSave number format string to the .z field
cellStylesfalseSave style/theme info to the .s field
cellDatesfalseStore dates as type d (default is n)
sheetStubsfalseCreate cell objects of type z for stub cells
sheetRows0If >0, read the first sheetRows rows **
bookDepsfalseIf true, parse calculation chains
bookFilesfalseIf true, add raw files to book object **
bookPropsfalseIf true, only parse enough to get book metadata **
bookSheetsfalseIf true, only parse enough to get the sheet names
bookVBAfalseIf true, expose vbaProject.bin to vbaraw field **
password""If defined and file is encrypted, use password **
WTFfalseIf 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.
  • bookSheets and bookProps combine to give both sets of information
  • Deps will be an empty object if bookDeps is falsy
  • 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 object. It does not parse the data.
  • 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.

The defaults are enumerated in bits/84_defaults.js

Input Type

Strings can be interpreted in multiple ways. The type parameter for read tells the library how to parse the data argument:

typeexpected input
"base64"string: base64 encoding of the file
"binary"string: binary string (n-th byte is data.charCodeAt(n))
"buffer"nodejs Buffer
"array"array: array of 8-bit unsigned int (n-th byte is data[n])
"file"string: filename that will be read and processed (nodejs only)

Guessing File Type

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 0Raw File TypeSpreadsheet Types
0xD0CFB ContainerBIFF 5/8 or password-protected XLSX/XLSB
0x09BIFF StreamBIFF 2/3/4/5
0x3CXML/HTMLSpreadsheetML or Flat ODS or UOS1 or HTML
0x50ZIP ArchiveXLSB or XLSX/M or ODS or UOS2
0xFEUTF8 TextSpreadsheetML or Flat ODS or UOS1

Writing Options

The exported write and writeFile functions accept an options argument:

Option NameDefaultDescription
typeOutput data encoding (see Output Type below)
cellDatesfalseStore dates as type d (default is n)
bookSSTfalseGenerate Shared String Table **
bookType"xlsx"Type of Workbook (see below for supported formats)
sheet""Name of Worksheet for single-sheet formats **
compressionfalseUse ZIP compression for ZIP-based formats **
  • 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. Formulae, formatting, and other niceties may not be serialized (pending CSF standardization)
  • 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 blow up in the presence of dates.

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:

bookTypefile extcontainersheetsDescription
xlsx.xlsxZIPmultiExcel 2007+ XML Format
xlsm.xlsmZIPmultiExcel 2007+ Macro XML Format
xlsb.xlsbZIPmultiExcel 2007+ Binary Format
ods.odsZIPmultiOpenDocument Spreadsheet
biff2.xlsnonesingleExcel 2.0 Worksheet format
fods.fodsnonemultiFlat OpenDocument Spreadsheet
csv.csvnonesingleComma Separated Values
  • 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.

Output Type

The type argument for write mirrors the type argument for read:

"base64"string: base64 encoding of the file
"binary"string: binary string (n-th byte is data.charCodeAt(n))
"buffer"nodejs Buffer
"file"string: name of file to be written (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 values may be stubbed. All other values are stored as strings. The function takes an options argument:

Option NameDefaultDescription
dateNFfmt 14Use specified date format in string output
cellDatesfalseStore dates as type d (default is n)
sheetStubsfalseCreate cell objects of type z for null values

To generate the example sheet:

var ws = XLSX.utils.aoa_to_sheet([

Formulae Output

XLSX.utils.sheet_to_formulae generates an array of commands that represent how a person would enter data into an application. Each entry is of the form A1-cell-address=formula-or-value. String literals are prefixed with a ' in accordance with Excel. For the example sheet:

> var o = XLSX.utils.sheet_to_formulae(ws);
> o.filter(function(v, i) { return i % 5 === 0; });
[ 'A1=\'S', 'F1=\'J', 'D2=4', 'B3=3', 'G3=8' ]

CSV and general DSV Output

As an alternative to the writeFile CSV type, XLSX.utils.sheet_to_csv also produces CSV output. The function takes an options argument:

Option NameDefaultDescription
FS",""Field Separator" delimiter between fields
RS"\n""Record Separator" delimiter between rows
dateNFfmt 14Use specified date format in string output
stripfalseRemove trailing field separators in each record **
blankrowstrueInclude blank lines in the CSV output
  • strip will remove trailing commas from each line under default FS/RS
  • blankrows must be set to false to skip blank lines.

For the example sheet:

> console.log(XLSX.utils.sheet_to_csv(ws));
> console.log(XLSX.utils.sheet_to_csv(ws, {FS:"\t"}));
S   h   e   e   t   J   S
1   2   3   4   5   6   7
2   3   4   5   6   7   8
> console.log(X.utils.sheet_to_csv(_ws,{FS:":",RS:"|"}));


XLSX.utils.sheet_to_json and the alias XLSX.utils.sheet_to_row_object_array generate different types of JS objects. The function takes an options argument:

Option NameDefaultDescription
rawfalseUse raw values (true) or formatted strings (false)
rangefrom WSOverride Range (see table below)
headerControl output format (see table below)
dateNFfmt 14Use specified date format in string output
defvalUse specified value in place of null or undefined
blankrows**Include blank lines in the output **
  • raw only affects cells which have a format code (.z) field or a formatted text (.w) field.
  • If header is specified, the first row is considered a data row; if header is not specified, the first row is the header row and not considered data.
  • When header is not specified, the conversion will automatically disambiguate header entries by affixing _ and a count starting at 1. For example, if three columns have header foo the output fields are foo, foo_1, foo_2
  • null values are returned when raw is true but are skipped when false.
  • If defval is not specified, null and undefined values are skipped normally. If specified, all null and undefined points will be filled with defval
  • When header is 1, the default is to generate blank rows. blankrows must be set to false to skip blank rows.
  • When header is not 1, the default is to skip blank rows. blankrows must be truthy to generate blank rows

range is expected to be one of:

(number)Use worksheet range but set starting row to the value
(string)Use specified range (A1-style bounded range string)
(default)Use worksheet range (ws['!ref'])

header is expected to be one of:

1Generate an array of arrays
"A"Row object keys are literal column labels
array of stringsUse specified strings as keys in row objects
(default)Read and disambiguate first row as keys

If header is not 1, the row object will contain the non-enumerable property __rowNum__ that represents the row of the sheet corresponding to the entry.

For the example sheet:

> console.log(X.utils.sheet_to_json(_ws));
[ { S: 1, h: 2, e: 3, e_1: 4, t: 5, J: 6, S_1: 7 },
  { S: 2, h: 3, e: 4, e_1: 5, t: 6, J: 7, S_1: 8 } ]

> console.log(X.utils.sheet_to_json(_ws, {header:1}));
[ [ 'S', 'h', 'e', 'e', 't', 'J', 'S' ],
  [ 1, 2, 3, 4, 5, 6, 7 ],
  [ 2, 3, 4, 5, 6, 7, 8 ] ]

> console.log(X.utils.sheet_to_json(_ws, {header:"A"}));
[ { A: 'S', B: 'h', C: 'e', D: 'e', E: 't', F: 'J', G: 'S' },
  { A: 1, B: 2, C: 3, D: 4, E: 5, F: 6, G: 7 },
  { A: 2, B: 3, C: 4, D: 5, E: 6, F: 7, G: 8 } ]
> console.log(X.utils.sheet_to_json(_ws, {header:["A","E","I","O","U","6","9"]}));
[ { '6': 'J', '9': 'S', A: 'S', E: 'h', I: 'e', O: 'e', U: 't' },
  { '6': 6, '9': 7, A: 1, E: 2, I: 3, O: 4, U: 5 },
  { '6': 7, '9': 8, A: 2, E: 3, I: 4, O: 5, U: 6 } ]

Example showing the effect of raw:

> _ws['A2'].w = "1";                         // set A2 formatted string value
> console.log(X.utils.sheet_to_json(_ws, {header:1}));
[ [ 'S', 'h', 'e', 'e', 't', 'J', 'S' ],
  [ '1', 2, 3, 4, 5, 6, 7 ],                 // <-- A2 uses the formatted string
  [ 2, 3, 4, 5, 6, 7, 8 ] ]
> console.log(X.utils.sheet_to_json(_ws, {header:1, raw:true}));
[ [ 'S', 'h', 'e', 'e', 't', 'J', 'S' ],
  [ 1, 2, 3, 4, 5, 6, 7 ],                   // <-- A2 uses the raw value
  [ 2, 3, 4, 5, 6, 7, 8 ] ]

File Formats

Despite the library name xlsx, it supports numerous spreadsheet file formats:

Excel Worksheet/Workbook Formats:-----::-----:
Excel 2007+ XML Formats (XLSX/XLSM):o::o:
Excel 2007+ Binary Format (XLSB BIFF12):o::o:
Excel 2003-2004 XML Format (XML "SpreadsheetML"):o::o:
Excel 97-2004 (XLS BIFF8):o:
Excel 5.0/95 (XLS BIFF5):o:
Excel 4.0 (XLS/XLW BIFF4):o:
Excel 3.0 (XLS BIFF3):o:
Excel 2.0/2.1 (XLS BIFF2):o::o:
Excel Supported Text Formats:-----::-----:
Delimiter-Separated Values (CSV/TSV/DSV):o:
Other Workbook/Worksheet Formats:-----::-----:
OpenDocument Spreadsheet (ODS):o::o:
Flat XML ODF Spreadsheet (FODS):o::o:
Uniform Office Format Spreadsheet (标文通 UOS1/UOS2):o:
Other Common Spreadsheet Output Formats:-----::-----:
HTML Tables:o:

Excel 2007+ XML (XLSX/XLSM)

XLSX and XLSM files are ZIP containers containing a series of XML files in accordance with the Open Packaging Conventions (OPC). The XLSM filetype, almost identical to XLSX, is used for files containing macros.

The format is standardized in ECMA-376 and later in ISO/IEC 29500. Excel does not follow the specification, and there are additional documents discussing how Excel deviates from the specification.

Excel 2.0-95 (BIFF2/BIFF3/BIFF4/BIFF5)

BIFF 2/3 XLS are single-sheet streams of binary records. Excel 4 introduced the concept of a workbook (XLW files) but also had single-sheet XLS format. The structure is largely similar to the Lotus 1-2-3 file formats. BIFF5/8/12 extended the format in various ways but largely stuck to the same record format.

There is no official specification for any of these formats. Excel 95 can write files in these formats, so record lengths and fields were backsolved by writing in all of the supported formats and comparing files. Excel 2016 can generate BIFF5 files, enabling a full suite of file tests starting from XLSX or BIFF2.

Excel 97-2004 Binary (BIFF8)

BIFF8 exclusively uses the Compound File Binary container format, splitting some content into streams within the file. At its core, it still uses an extended version of the binary record format from older versions of BIFF.

The MS-XLS specification covers the basics of the file format, and other specifications expand on serialization of features like properties.

Excel 2003-2004 (SpreadsheetML)

Predating XLSX, SpreadsheetML files are simple XML files. There is no official and comprehensive specification, although MS has released whitepapers on the format. Since Excel 2016 can generate SpreadsheetML files, backsolving is pretty straightforward.

Excel 2007+ Binary (XLSB, BIFF12)

Introduced in parallel with XLSX, the XLSB filetype combines BIFF architecture with the content separation and ZIP container of XLSX. For the most part nodes in an XLSX sub-file can be mapped to XLSB records in a corresponding sub-file.

The MS-XLSB specification covers the basics of the file format, and other specifications expand on serialization of features like properties.

OpenDocument Spreadsheet (ODS/FODS) and Uniform Office Spreadsheet (UOS1/2)

ODS is an XML-in-ZIP format akin to XLSX while FODS is an XML format akin to SpreadsheetML. Both are detailed in the OASIS standard, but tools like LO/OO add undocumented extensions.

UOS is a very similar format, and it comes in 2 varieties corresponding to ODS and FODS respectively. For the most part, the difference between the formats lies in the names of tags and attributes.

Comma-Separated Values

Excel CSV deviates from RFC4180 in a number of important ways. The generated CSV files should generally work in Excel although they may not work in RFC4180 compatible readers.


Excel HTML worksheets include special metadata encoded in styles. For example, mso-number-format is a localized string containing the number format. Despite the metadata the output is valid HTML, although it does accept bare & symbols.


make test will run the node-based tests. By default it runs tests on files in every supported format. To test a specific file type, set FMTS to the format you want to test. Feature-specific tests are avaialble with make test_misc

$ make test        # run full tests
$ make test_xls    # only use the XLS test files
$ make test_xlsx   # only use the XLSX test files
$ make test_xlsb   # only use the XLSB test files
$ make test_xml    # only use the XLSB test files
$ make test_ods    # only use the XLSB test files

To enable all errors, set the environment variable WTF=1:

$ make test        # run full tests
$ WTF=1 make test  # enable all error messages

Flow and JSHint/JSCS checks are available:

$ make lint        # JSHint and JSCS checks
$ make flow        # make lint + Flow checking

The core in-browser tests are available at tests/test.html within this repo. Start a local server and navigate to that directory to run the tests.

To run the full in-browser tests, clone the repo for and replace the xlsx.js file (then fire up the browser and go to stress.html):

$ cp xlsx.js ../
$ cd ../
$ simplehttpserver # or "python -mSimpleHTTPServer" or "serve"
$ open -a http://localhost:8000/stress.html

Tested Environments

  • NodeJS 0.8, 0.9, 0.10, 0.11, 0.12, 4.x, 5.x, 6.x, 7.x
  • IE 6/7/8/9/10/11 (IE6-9 browsers require shims for interacting with client)
  • Chrome 24+
  • Safari 6+
  • FF 18+

Tests utilize the mocha testing framework. Travis-CI and Sauce Labs links:

Test Files

Test files are housed in another repo.

Running make init will refresh the test_files submodule and get the files.


Due to the precarious nature of the Open Specifications Promise, it is very important to ensure code is cleanroom. Consult

The xlsx.js file is constructed from the files in the bits subdirectory. The build script (run make) will concatenate the individual bits to produce the script. Before submitting a contribution, ensure that running make will produce the xlsx.js file exactly. The simplest way to test is to add the script:

$ git add xlsx.js
$ make clean
$ make
$ git diff xlsx.js

To produce the dist files, run make dist. The dist files are updated in each version release and should not be committed between versions.


Please consult the attached LICENSE file for details. All rights not explicitly granted by the Apache 2.0 License are reserved by the Original Author.


ISO/IEC 29500:2012(E) "Information technology — Document description and processing languages — Office Open XML File Formats"

OSP-covered specifications:

  • [MS-XLSB]: Excel (.xlsb) Binary File Format
  • [MS-XLSX]: Excel (.xlsx) Extensions to the Office Open XML SpreadsheetML File Format
  • [MS-OE376]: Office Implementation Information for ECMA-376 Standards Support
  • [MS-CFB]: Compound File Binary File Format
  • [MS-XLS]: Excel Binary File Format (.xls) Structure Specification
  • [MS-ODATA]: Open Data Protocol (OData)
  • [MS-OFFCRYPTO]: Office Document Cryptography Structure
  • [MS-OLEDS]: Object Linking and Embedding (OLE) Data Structures
  • [MS-OLEPS]: Object Linking and Embedding (OLE) Property Set Data Structures
  • [MS-OSHARED]: Office Common Data Types and Objects Structures
  • [MS-ODRAW]: Office Drawing Binary File Format
  • [MS-ODRAWXML]: Office Drawing Extensions to Office Open XML Structure
  • [MS-OVBA]: Office VBA File Format Structure
  • [MS-CTXLS]: Excel Custom Toolbar Binary File Format
  • [MS-XLDM]: Spreadsheet Data Model File Format
  • [MS-EXSPXML3]: Excel Calculation Version 2 Web Service XML Schema
  • [XLS]: Microsoft Office Excel 97-2007 Binary File Format Specification
  • [MS-OI29500]: Office Implementation Information for ISO/IEC 29500 Standards Support

Open Document Format for Office Applications Version 1.2 (29 September 2011)

Worksheet File Format (From Lotus) December 1984


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