File

The File interface provides information about files and allows JavaScript in a web page to access their content.

File objects are generally retrieved from a FileList object returned as a result of a user selecting files using the <input> element, from a drag and drop operation's DataTransfer object, or from the mozGetAsFile() API on an HTMLCanvasElement.

A File object is a specific kind of a Blob, and can be used in any context that a Blob can. In particular, FileReader, URL.createObjectURL(), createImageBitmap(), and XMLHttpRequest.send() accept both Blobs and Files.

See Using files from web applications for more information and examples.

Constructor

File()
Returns a newly constructed File.

Instance properties

File.prototype.lastModified Read only
Returns the last modified time of the file, in millisecond since the UNIX epoch (January 1st, 1970 at Midnight).
File.prototype.lastModifiedDate This deprecated API should no longer be used, but will probably still work. Read only
Returns the last modified Date of the file referenced by the File object.
File.prototype.nameRead only
Returns the name of the file referenced by the File object.
File.prototype.webkitRelativePath This API has not been standardized. Read only
Returns the path the URL of the File is relative to.

File implements Blob, so it also has the following properties available to it:

File.prototype.size Read only
Returns the size of the file in bytes.
File.prototype.type Read only
Returns the MIME type of the file.

Instance methods

The File interface doesn't define any methods, but inherits methods from the Blob interface:

Blob.prototype.slice([start[, end[, contentType]]])
Returns a new Blob object containing the data in the specified range of bytes of the source Blob.
Blob.prototype.stream()
Transforms the File into a ReadableStream that can be used to read the File contents.
Blob.prototype.text()
Transforms the File into a stream and reads it to completion. It returns a promise that resolves with a USVString (text).
Blob.prototype.arrayBuffer()
Transforms the File into a stream and reads it to completion. It returns a promise that resolves with an ArrayBuffer.

Specifications

Specification Status Comment
File API
The definition of 'The File interface' in that specification.
Working Draft Initial definition.

Browser compatibility

BCD tables only load in the browser

See also