Web/API/Blob/slice

The Blob interface's slice() method creates and returns a new Blob object which contains data from a subset of the blob on which it's called.

Syntax

var newBlob = blob.slice(start, end, contentType);

Parameters

start Optional: An index into the Blob indicating the first byte to include in the new Blob. If you specify a negative value, it's treated as an offset from the end of the Blob toward the beginning. For example, -10 would be the 10th from last byte in the Blob. The default value is 0. If you specify a value for start that is larger than the size of the source Blob, the returned Blob has size 0 and contains no data.
end Optional: An index into the Blob indicating the first byte that will *not* be included in the new Blob (i.e. the byte exactly at this index is not included). If you specify a negative value, it's treated as an offset from the end of the Blob toward the beginning. For example, -10 would be the 10th from last byte in the Blob. The default value is size.
contentType Optional: The content type to assign to the new Blob; this will be the value of its type property. The default value is an empty string.

Return value

A new Blob object containing the specified subset of the data contained within the blob on which this method was called. The original blob is not altered.

Specifications

Specification	Status	Comment
File APIThe definition of 'Blob.slice()' in that specification.	Working Draft	Initial definition

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
`slice()`	Chrome Full support 21 Full support 21 No support 5 — 25 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	Edge Full support 12	Firefox Full support 13 Notes' Full support 13 Notes' Notes' Prior to Firefox 12, there was a bug that affected the behavior of `Blob.slice()`; it did not work for `start` and `end` positions outside the range of signed 64-bit values; it has now been fixed to support unsigned 64-bit values. No support 5 — 13 Prefixed' Prefixed' Implemented with the vendor prefix: moz	IE Full support 10	Opera Full support 12	Safari Full support 5.1 Prefixed' Full support 5.1 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	WebView Android Full support Yes	Chrome Android Full support 25 Full support 25 No support 18 — 25 Prefixed' Prefixed' Implemented with the vendor prefix: webkit	Firefox Android Full support 14	Opera Android Full support Yes	Safari iOS Full support Yes	Samsung Internet Android Full support 1.5 Full support 1.5 No support 1.0 — 1.5 Prefixed' Prefixed' Implemented with the vendor prefix: webkit

Legend

Full support: Full support
See implementation notes.': See implementation notes.
Requires a vendor prefix or different name for use.': Requires a vendor prefix or different name for use.