Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

Note: The three non-standard interfaces IDBMutableFile, IDBFileHandle, and IDBFileRequest are disabled by default. Consider using the File and Directory Entries API instead.

The IDBFileHandle interface provides tools to deal with a given file with all the necessary locks.

Instance properties

IDBFileHandle.fileHandle Read only

The IDBMutableFile object from which the lock was opened.

IDBFileHandle.mode Read only

The mode for accessing the file; can be readonly or readwrite. Read only

A flag indicating if the file can be accessed (true) or not (false).


The position of the reading/writing pointer within the file.

Instance methods


Allows to retrieve the file metadata (size and date of the last modification).


Allows to retrieve a part of the content of the file as an ArrayBuffer.


Allows to retrieve a part of the content of the file as a string.


Allows to write some data in the file starting at the location offset.


Allows to write some data at the end of the file..


Allows to truncate the file's content.


Allows to guarantee that any buffered data has been transferred to disk.


Makes the IDBFileHandle inactive and cancels all ongoing operations.

Events Handler


Fired when a read or write operation is successful.


Fired when the abort() method is called.


Fired when something goes wrong.


This feature is not part of any current specification. It is no longer on track to become a standard.

Browser compatibility

This interface is not supported by any current browser. From Firefox 102 it is behind the preference dom.fileHandle.enabled.

See also