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 append() method of the IDBFileHandle interface write additional data at the end of the file.

The write operation is performed at the end of the file, regardless of the IDBFilehandle.location value, and actually sets the value of this property to null.





The data to write into the file. It can be a string or an ArrayBuffer.

Return value

An IDBFileRequest object to handle the success or failure of the operation.


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

Browser compatibility

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

See also