license: Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
As object that allows you to create and write data to a file.
readyState: One of the three possible states, either INIT
, WRITING
, or DONE
.
fileName: The name of the file to be written. (DOMString)
length: The length of the file to be written. (long)
position: The current position of the file pointer. (long)
error: An object containing errors. (FileError)
onwritestart: Called when the write starts. (Function)
onwrite: Called when the request has completed successfully. (Function)
onabort: Called when the write has been aborted. For instance, by invoking the abort() method. (Function)
onerror: Called when the write has failed. (Function)
onwriteend: Called when the request has completed (either in success or failure). (Function)
The following property is not supported:
progress.loaded
/progress.total
. (Function)abort: Aborts writing the file.
seek: Moves the file pointer to the specified byte.
truncate: Shortens the file to the specified length.
write: Writes data to the file.
The FileWriter
object offers a way to write UTF-8 encoded files to the device file system. Applications respond to writestart
, progress
, write
, writeend
, error
, and abort
events.
Each FileWriter
corresponds to a single file, to which data can be written many times. The FileWriter
maintains the file's position
and length
attributes, which allow the app to seek
and write
anywhere in the file. By default, the FileWriter
writes to the beginning of the file, overwriting existing data. Set the optional append
boolean to true
in the FileWriter
's constructor to write to the end of the file.
Text data is supported by all platforms listed below. Text is encoded as UTF-8 before being written to the filesystem. Some platforms also support binary data, which can be passed in as either an ArrayBuffer or a Blob.
Text and Binary Support:
Text-only Support:
function win(writer) { // fast forwards file pointer to end of file writer.seek(writer.length); }; var fail = function(evt) { console.log(error.code); }; entry.createWriter(win, fail);
function win(writer) { writer.truncate(10); }; var fail = function(evt) { console.log(error.code); }; entry.createWriter(win, fail);
function win(writer) { writer.onwrite = function(evt) { console.log("write success"); }; writer.write("some sample text"); }; var fail = function(evt) { console.log(error.code); }; entry.createWriter(win, fail);
function win(writer) { var data = new ArrayBuffer(5), dataView = new Int8Array(data); for (i=0; i < 5; i++) { dataView[i] = i; } writer.onwrite = function(evt) { console.log("write success"); }; writer.write(data); }; var fail = function(evt) { console.log(error.code); }; entry.createWriter(win, fail);
function win(writer) { writer.onwrite = function(evt) { console.log("write success"); }; writer.seek(writer.length); writer.write("appended text"); }; var fail = function(evt) { console.log(error.code); }; entry.createWriter(win, fail);
function win(writer) { writer.onwrite = function(evt) { console.log("write success"); }; writer.write("some sample text"); writer.abort(); }; var fail = function(evt) { console.log(error.code); }; entry.createWriter(win, fail);
<!DOCTYPE html> <html> <head> <title>FileWriter Example</title> <script type="text/javascript" charset="utf-8" src="cordova.js"></script> <script type="text/javascript" charset="utf-8"> // Wait for device API libraries to load // document.addEventListener("deviceready", onDeviceReady, false); // device APIs are available // function onDeviceReady() { window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, gotFS, fail); } function gotFS(fileSystem) { fileSystem.root.getFile("readme.txt", {create: true, exclusive: false}, gotFileEntry, fail); } function gotFileEntry(fileEntry) { fileEntry.createWriter(gotFileWriter, fail); } function gotFileWriter(writer) { writer.onwriteend = function(evt) { console.log("contents of file now 'some sample text'"); writer.truncate(11); writer.onwriteend = function(evt) { console.log("contents of file now 'some sample'"); writer.seek(4); writer.write(" different text"); writer.onwriteend = function(evt){ console.log("contents of file now 'some different text'"); } }; }; writer.write("some sample text"); } function fail(error) { console.log(error.code); } </script> </head> <body> <h1>Example</h1> <p>Write File</p> </body> </html>