---

title: “async(type[, onUpdate])” layout: default section: api

Return a Promise of the content in the asked type.

Returns : A Promise of the content.

Since: v3.0.0

Arguments

name	type	description
type	String	the type of the result. More.
onUpdate	Function	an optional function called on each internal update with the metadata. More.

type option

Possible values for type :

• base64 : the result will be a string, the binary in a base64 form.
• text (or string): the result will be an unicode string.
• binarystring: the result will be a string in “binary” form, using 1 byte per char (2 bytes).
• array: the result will be an Array of bytes (numbers between 0 and 255).
• uint8array : the result will be a Uint8Array. This requires a compatible browser.
• arraybuffer : the result will be a ArrayBuffer. This requires a compatible browser.
• blob : the result will be a Blob. This requires a compatible browser.
• nodebuffer : the result will be a nodejs Buffer. This requires nodejs.

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

zip.file("image.png").async("uint8array").then(function (u8) {
    // ...
});

onUpdate callback

If specified, this function will be called each time a chunk is pushed to the output stream (or internally accumulated).

The function takes a metadata object which contains information about the ongoing process.

Metadata : the metadata are :

name	type	description
percent	number	the percent of completion (a double between 0 and 100)

zip.file("image.png").async("uint8array", function updateCallback(metadata) {
    console.log("progression: " + metadata.percent.toFixed(2) + " %");
}).then(function (u8) {
    // ...
})

Other examples

zip
.file("my_text.txt")
.async("string")
.then(function success(content) {
    // use the content
}, function error(e) {
    // handle the error
});