elemental.html

Interface Blob

All Known Subinterfaces:

File

All Known Implementing Classes:

JsBlob, JsFile

public interface Blob

This is an experimental feature
Because this feature is still in development in some browsers, check the compatibility table for the proper prefixes to use in various browsers.

A Blob object represents a file-like object of immutable, raw data. Blobs represent data that isn't necessarily in a JavaScript-native format. The File interface is based on Blob, inheriting blob functionality and expanding it to support files on the user's system.

An easy way to construct a Blob is by using the BlobBuilder interface, which lets you iteratively append data to a blob, then retrieve the completed blob when you're ready to use it for something. Another way is to use the slice() method to create a blob that contains a subset of another blob's data.

Note: The slice() method has vendor prefixes: blob.mozSlice() for Firefox and blob.webkitSlice() for Chrome. An old version of the slice() method, without vendor prefixes, had different semantics, as described below.

Method Summary

Modifier and Type	Method and Description
double	getSize() The size, in bytes, of the data contained in the Blob object.
String	getType() An ASCII-encoded string, in all lower case, indicating the MIME type of the data contained in the Blob.
Blob	webkitSlice()
Blob	webkitSlice(double start)
Blob	webkitSlice(double start, double end)
Blob	webkitSlice(double start, double end, String contentType)

Method Detail

getSize

double getSize()

The size, in bytes, of the data contained in the Blob object. Read only.

getType

String getType()

An ASCII-encoded string, in all lower case, indicating the MIME type of the data contained in the Blob. If the type is unknown, this string is empty. Read only.

webkitSlice

Blob webkitSlice()

webkitSlice

Blob webkitSlice(double start)

webkitSlice

Blob webkitSlice(double start,
                 double end)

webkitSlice

Blob webkitSlice(double start,
                 double end,
                 String contentType)