FileReader extension type

The FileReader object lets web applications asynchronously read the contents of files (or raw data buffers) stored on the user's computer, using File or Blob objects to specify the file or data to read.

File objects may be obtained from a FileList object returned as a result of a user selecting files using the input element, or from a drag and drop operation's DataTransfer object.

FileReader can only access the contents of files that the user has explicitly selected, either using an HTML <input type="file"> element or by drag and drop. It cannot be used to read a file by pathname from the user's file system. To read files on the client's file system by pathname, use the File System Access API. To read server-side files, use fetch, with CORS permission if reading cross-domain.

on

JSObject

Implemented types

Constructors

FileReader(): factory

Properties

error → DOMException?: no setter
hashCode → int: The hash code for this object.
no setterinherited
onabort ↔ EventHandler?: getter/setter pair
onerror ↔ EventHandler?: getter/setter pair
onload ↔ EventHandler?: getter/setter pair
onloadend ↔ EventHandler?: getter/setter pair
onloadstart ↔ EventHandler?: getter/setter pair
onprogress ↔ EventHandler?: getter/setter pair
readyState → int: no setter
result → JSAny?: no setter
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited

Methods

abort() → void: The abort method of the FileReader interface aborts the read operation. Upon return, the FileReader.readyState will be DONE.
addEventListener(String type, EventListener? callback, [JSAny options]) → void: The addEventListener() method of the EventTarget interface sets up a function that will be called whenever the specified event is delivered to the target.
inherited
dispatchEvent(Event event) → bool: The dispatchEvent() method of the EventTarget sends an Event to the object, (synchronously) invoking the affected event listeners in the appropriate order. The normal event processing rules (including the capturing and optional bubbling phase) also apply to events dispatched manually with dispatchEvent().
inherited
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
readAsArrayBuffer(Blob blob) → void: The readAsArrayBuffer() method of the FileReader interface is used to start reading the contents of a specified Blob or File. When the read operation is finished, the FileReader.readyState becomes DONE, and the FileReader/loadend_event is triggered. At that time, the FileReader.result attribute contains an ArrayBuffer representing the file's data.
readAsBinaryString(Blob blob) → void: Note: This method is deprecated in favor of FileReader.readAsArrayBuffer.
readAsDataURL(Blob blob) → void: The readAsDataURL method of the FileReader interface is used to read the contents of the specified Blob or File. When the read operation is finished, the FileReader.readyState becomes DONE, and the FileReader/loadend_event is triggered. At that time, the FileReader.result attribute contains the data as a data: URL representing the file's data as a base64 encoded string.
readAsText(Blob blob, [String encoding]) → void: The readAsText() method of the FileReader interface is used to read the contents of the specified Blob or File. When the read operation is complete, the FileReader.readyState is changed to DONE, the FileReader/loadend_event event is triggered, and the FileReader.result property contains the contents of the file as a text string.
removeEventListener(String type, EventListener? callback, [JSAny options]) → void: The removeEventListener() method of the EventTarget interface removes an event listener previously registered with EventTarget.addEventListener from the target. The event listener to be removed is identified using a combination of the event type, the event listener function itself, and various optional options that may affect the matching process; see Matching event listeners for removal.
inherited
toString() → String: A string representation of this object.
inherited

Operators

operator ==(Object other) → bool: The equality operator.
inherited

Static Properties

DONE → int: no setter
EMPTY → int: no setter
LOADING → int: no setter