Provides methods to monitor the asynchronous writing of blobs to disk with a usage of progress events and event handler attributes.

An instance of this object is obtained by calling the createWriter, which returns a FileWriter associated with a file that is being written to.

The attributes of the FileWriter object are listed below:


Constant Description Type
DONE The entire Blob has been written to the file, an error occurred during the write, or the write was aborted using abort. The FileWriter is no longer writing the blob. unsigned short
INIT The object has been constructed, but there is no pending write. unsigned short
WRITING The blob is being written. unsigned short


Attribute Description Type
readyState Returns the current state of the FileWriter object, which takes one of the following values: "INIT", "WRITING", "DONE". unsigned short
error The last error that occurred on the FileWriter object. DOMError
position The byte offset, at which the next write to the file occurs. This must be no greater than length. A newly created FileWriter object instance has the position attribute set to 0 (zero). int
length The length of the file. If the user does not have read access to the file, this is the highest byte offset at which the user has written. string
queueOperations Specifies whether FileWriter should queue subsequent operations or not. boolean

Event handlers

Attribute Description Type
onwritestart Handler for writestart events. Function
onprogress Handler for progress events. Function
onwrite Handler for write events. Function
onabort Handler for abort events. Function
onerror Handler for error events. Function
onwriteend Handler for writeend events. Function


Name Description

Sets the file position at which the next write will occur.


Changes the length of the file to that specified. If shortening the file, the data beyond the new length is discarded. If extending the file, the existing data is zero-padded up to the new length.


Writes the supplied data to the file, starting at the offset indicated by the value of the "position" attribute.


Terminates the algorithm for the currently executed method.

Related topics

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