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 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 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 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
File API # file-section

Browser compatibility

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