Web/API/BlobBuilder

ObsoleteThis feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

The BlobBuilder interface provides an easy way to construct Blob objects. Just create a BlobBuilder and append chunks of data to it by calling the append() method. When you're done building your blob, call getBlob() to retrieve a Blob containing the data you sent into the blob builder.

Note: The BlobBuilder interface has been deprecated in favor of the newly introduced Blob constructor.

Method overview

void append(in ArrayBuffer data);

void append(in Blob data);

void append(in String data, [optional] in String endings);

Blob getBlob([optional] in DOMString contentType);

File getFile(in DOMString name, [optional] in DOMString contentType);

Methods

append()

Appends the contents of the specified JavaScript object to the Blob being built. If the value you specify isn't a Blob, ArrayBuffer, or String, the value is coerced to a string before being appended to the blob.

void append(
  in ArrayBuffer data
);

void append(
  in Blob data
);


void append(
  in String data,
  [optional] in String endings
);

Parameters

data

The data to append to the Blob being constructed.

endings

Specifies how strings containing \n are to be written out. This can be "transparent" (endings unchanged) or "native" (endings changed to match host OS filesystem convention). The default value is "transparent".

getBlob()

Returns the Blob object that has been constructed using the data passed through calls to append().

Blob getBlob(
  in DOMString contentType Optional
);

Parameters

contentType Optional

The MIME type of the data to be returned in the Blob. This will be the value of the Blob object's type property.

Return value

A Blob object containing all of the data passed to any calls to append() made since the BlobBuilder was created. This also resets the BlobBuilder so that the next call to append() is starting a new, empty blob.

getFile() '

Returns a File object.

File getFile(
  in DOMString name,
  [optional] in DOMString contentType
); 

Parameters

name

The file name.

contentType Optional

The MIME type of the data to be returned in the File. This will be the value of the File object's type property.

Return value

A File object.

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
BlobBuilder Deprecated'Non-standard'	Chrome No support 8 — 24 Prefixed' No support 8 — 24 Prefixed' Prefixed' Implemented with the vendor prefix: WebKit	Edge No support 12 — 79 Prefixed' No support 12 — 79 Prefixed' Prefixed' Implemented with the vendor prefix: MS	Firefox No support 6 — 18 Prefixed' Notes' No support 6 — 18 Prefixed' Notes' Prefixed' Implemented with the vendor prefix: Moz Notes' Starting in Firefox 14, using MozBlobBuilder will show a warning message in the web console that the use of MozBlobBuilder is deprecated and suggests to use Blob constructor instead.	IE Full support 10 Prefixed' Full support 10 Prefixed' Prefixed' Implemented with the vendor prefix: MS	Opera No support No	Safari No support No	WebView Android No support 3 — ≤37 Prefixed' No support 3 — ≤37 Prefixed' Prefixed' Implemented with the vendor prefix: WebKit	Chrome Android No support 18 — 25 Prefixed' No support 18 — 25 Prefixed' Prefixed' Implemented with the vendor prefix: WebKit	Firefox Android No support 6 — 18 Prefixed' Notes' No support 6 — 18 Prefixed' Notes' Prefixed' Implemented with the vendor prefix: Moz Notes' Starting in Firefox 14, using MozBlobBuilder will show a warning message in the web console that the use of MozBlobBuilder is deprecated and suggests to use Blob constructor instead.	Opera Android No support No	Safari iOS No support No	Samsung Internet Android No support 1.0 — 1.5 Prefixed' No support 1.0 — 1.5 Prefixed' Prefixed' Implemented with the vendor prefix: WebKit

Legend

Full support  

Full support

No support  

No support

Non-standard. Expect poor cross-browser support.'

Non-standard. Expect poor cross-browser support.

Deprecated. Not for use in new websites.'

Deprecated. Not for use in new websites.

See implementation notes.'

See implementation notes.

Requires a vendor prefix or different name for use.'

Requires a vendor prefix or different name for use.

See also

• File API Specification: BlobBuilderED
• Blob
• File

BlobBuilder by Mozilla Contributors is licensed under CC-BY-SA 2.5.