generateAsync(options[, onUpdate])

Description : Generates the complete zip file at the current folder level.


name type default description
options object   the options to generate the zip file :
options.compression string STORE (no compression) the default file compression method to use. Available methods are STORE and DEFLATE. You can also provide your own compression method.
options.compressionOptions object null the options to use when compressing the file, see below.
options.type string   The type of zip to return, see below for the other types.
options.comment string   The comment to use for the zip file.
options.mimeType string application/zip mime-type for the generated file. Useful when you need to generate a file with a different extension, ie: “.ods”.
options.platform string DOS The platform to use when generating the zip file.
options.encodeFileName function encode with UTF-8 the function to encode the file name / comment.
options.streamFiles boolean false Stream the files and create file descriptors, see below.
onUpdate function   The optional function called on each internal update with the metadata.

Possible values for type :

  • base64 : the result will be a string, the binary in a base64 form.
  • binarystring (or string, deprecated) : the result will be a string in “binary” form, using 1 byte per char (2 bytes).
  • uint8array : the result will be a Uint8Array containing the zip. This requires a compatible browser.
  • arraybuffer : the result will be a ArrayBuffer containing the zip. This requires a compatible browser.
  • blob : the result will be a Blob containing the zip. This requires a compatible browser.
  • nodebuffer : the result will be a nodejs Buffer containing the zip. This requires nodejs.

Note : when using type = “uint8array”, “arraybuffer” or “blob”, be sure to check if the browser supports it (you can use

The compressionOptions parameter depends on the compression type. With STORE (no compression), this parameter is ignored. With DEFLATE, you can give the compression level with compressionOptions : {level:6} (or any level between 1 (best speed) and 9 (best compression)).

Note : if the entry is already compressed (coming from a compressed zip file), calling generateAsync() with a different compression level won’t update the entry. The reason is simple : JSZip doesn’t know how compressed the content was and how to match the compression level with the implementation we use.

Note for the comment option : the zip format has no flag or field to give the encoding of this field and JSZip will use UTF-8. With non ASCII characters you might get encoding issues if the file archiver doesn’t use UTF-8 to decode the comment.

Note for the streamFiles option : in a zip file, the size and the crc32 of the content are placed before the actual content : to write it we must process the whole file. When this option is false (the default) the processed file is held in memory. It takes more memory but generates a zip file which should be read by every program. When this options is true, we stream the file and use data descriptors at the end of the entry. This option uses less memory but some program might not support data descriptors (and won’t accept the generated zip file).

If not set, JSZip will use the field comment on its options.

Possible values for platform : DOS and UNIX. It also accepts nodejs process.platform values. When using DOS, the attribute dosPermissions of each file is used. When using UNIX, the attribute unixPermissions of each file is used.

If you set the platform value on nodejs, be sure to use process.platform. fs.stats returns a non executable mode for folders on windows, if you force the platform to UNIX the generated zip file will have a strange behavior on UNIX platforms.

About encodeFileName :

By default, JSZip uses UTF-8 to encode the file names / comments. You can use this method to force an other encoding. Note : the encoding used is not stored in a zip file, not using UTF-8 may lead to encoding issues. The function takes a string and returns a bytes array (Uint8Array or Array).

Metadata : the metadata are :

name type description
percent number the percent of completion (a double between 0 and 100)
currentFile string the name of the current file being processed, if any.

Returns : A Promise of the generated zip file.

Throws : An exception if the asked type is not available in the browser, see


.then(function (content) {
    // see FileSaver.js
    saveAs(content, "");
.then(function (content) {
zip.folder("folder_1").folder("folder_2").file("hello.txt", "hello");
// zip now contains:
// folder_1/
// folder_1/folder_2/
// folder_1/folder_2/hello.txt

.then(function (content) {
    // relative to folder_1/, this file only contains:
    // folder_2/
    // folder_2/hello.txt
    require("fs").writeFile("", content, function(err){/*...*/});
// on nodejs
zip.file(pathname, content, {
    date: stat.mtime,
    unixPermissions: stat.mode

// ...

    type: 'nodebuffer',
    platform: process.platform

Using a custom charset :

// using iconv-lite for example
var iconv = require('iconv-lite');

    type: 'uint8array',
    encodeFileName: function (string) {
        return iconv.encode(string, 'your-encoding');
//This example will Generate a Open Document Spreasheet, with the correct mime type
var zip = new JSZip();
zip.file("mimetype", "application/vnd.oasis.opendocument.spreadsheet");
var conf2 = zip.folder("Configurations2");

var manifest = "<..."; //xml containing manifest.xml
var styles = "<..."; //xml containing styles.xml
var settings = "<..."; //xml containing settings.xml
var meta = "<..."; //xml containing meta.xml
var content = "<..."; //xml containing content.xml

var metaInf = zip.folder("META-INF");
metaInf.file("manifest.xml", manifest);
zip.file("styles.xml", styles);
zip.file("settings.xml", settings);
zip.file("meta.xml", meta);
zip.file("content.xml", content);

//Generate the file
    type: "blob",
    mimeType: "application/ods",
    compression: "DEFLATE"
}).then(function (odsFile) {
    var url = window.URL.createObjectURL(odsFile);
    var link = document.getElementById("link"); //I suppose you'll have a link with this id :) = "testjs.ods";
    link.href = url;