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Blob.slice

The Blob.slice() method is used to create a new Blob object containing the data in the specified range of bytes of the source Blob.

Note: Be aware that the slice() method has vendor prefixes on some browsers and versions: blob.mozSlice() for Firefox 12 and earlier and blob.webkitSlice() in Safari. An old version of the slice() method, without vendor prefixes, had different semantics, and is obsolete.

Syntax

var blob = instanceOfBlob.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 string 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 string 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 data from the source Blob.

Specifications

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

Browser compatibilityUpdate compatibility data on GitHub

	Desktop
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	21 21 5 — 21 Prefixed Prefixed Requires the vendor prefix: webkit	12	13 13 Prior to Gecko 12.0 (Firefox 12.0 / Thunderbird 12.0 / SeaMonkey 2.9), 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. 5 — 13 Prefixed Prefixed Requires the vendor prefix: moz	10	12	5.1 Prefixed 5.1 Prefixed Prefixed Requires the vendor prefix: webkit