FileSystemFileEntry.createWriter()

The FileSystemFileEntry interface's method createWriter() returns a FileWriter object which can be used to write data into the file represented by the directory entry.

Syntax

FileSystemFileEntry.createWriter(successCallback[, errorCallback]);

Parameters

successCallback

A callback function which is called when the FileWriter has been created successfully; the FileWriter is passed into the callback as the only parameter.

errorCallback Optional

If provided, this must be a method which is caled when an error occurs while trying to create the FileWriter. This callback receives as input a FileError object describing the error.

Return value

undefined.

Example

This example establishes a method, writeToFileEntry(), which outputs a text string to the file corresponding to the passed-in directory entry.

function writeToFileEntry(entry, text) {
  entry.createWriter(function(fileWriter)) {
    let data = Blob([text], { type: "text/plain" });
    fileWriter.write(data);
  }, function(fileError) {
    /* do whatever to handle the error */
  });
}

The success callback for the createWriter() call takes the text which was passed in and creates a new Blob object of type text/plain that contains the passed text. This blob is then output to the FileWriter object to be written to the file.

Specifications

This API has no official W3C or WHATWG specification.

Browser compatibility

[1] While the createWriter() method exists in Firefox 50, it is not supported, and immediately reports an NS_ERROR_DOM_SECURITY_ERR error to the error callback.  The method was removed entirely in Firefox 52.

See also

• File and Directory Entries API
• Introduction to the File System API