---
title: File
description: Read/write files on the device.
---

|AppVeyor|Travis CI|
|:-:|:-:|
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cordova-plugin-file

This plugin implements a File API allowing read/write access to files residing on the device.

This plugin is based on several specs, including :
The HTML5 File API
http://www.w3.org/TR/FileAPI/

The Directories and System extensions
Latest:
http://www.w3.org/TR/2012/WD-file-system-api-20120417/
Although most of the plugin code was written when an earlier spec was current:
http://www.w3.org/TR/2011/WD-file-system-api-20110419/

It also implements the FileWriter spec :
http://dev.w3.org/2009/dap/file-system/file-writer.html

>Note While the W3C FileSystem spec is deprecated for web browsers, the FileSystem APIs are supported in Cordova applications with this plugin for the platforms listed in the _Supported Platforms_ list, with the exception of the Browser platform.

To get a few ideas how to use the plugin, check out the sample at the bottom of this page. For additional examples (browser focused), see the HTML5 Rocks' FileSystem article.

For an overview of other storage options, refer to Cordova's
storage guide.

This plugin defines global cordova.file object.

Although in the global scope, it is not available until after the deviceready event.

document.addEventListener("deviceready", onDeviceReady, false);
function onDeviceReady() {
console.log(cordova.file);
}

Installation

cordova plugin add cordova-plugin-file

Supported Platforms

- Android
- iOS
- OS X
- Windows*
- Browser

\* _These platforms do not support FileReader.readAsArrayBuffer nor FileWriter.write(blob)._

Where to Store Files

As of v1.2.0, URLs to important file-system directories are provided.
Each URL is in the form _file:///path/to/spot/_, and can be converted to a
DirectoryEntry using window.resolveLocalFileSystemURL().

* cordova.file.applicationDirectory - Read-only directory where the application
is installed. (_iOS_, _Android_, _BlackBerry 10_, _OSX_, _windows_)

* cordova.file.applicationStorageDirectory - Root directory of the application's
sandbox; on iOS & windows this location is read-only (but specific subdirectories [like
/Documents on iOS or /localState on windows] are read-write). All data contained within
is private to the app. (_iOS_, _Android_, _BlackBerry 10_, _OSX_)

* cordova.file.dataDirectory - Persistent and private data storage within the
application's sandbox using internal memory (on Android, if you need to use
external memory, use .externalDataDirectory). On iOS, this directory is not
synced with iCloud (use .syncedDataDirectory). (_iOS_, _Android_, _BlackBerry 10_, _windows_)

* cordova.file.cacheDirectory - Directory for cached data files or any files
that your app can re-create easily. The OS may delete these files when the device
runs low on storage, nevertheless, apps should not rely on the OS to delete files
in here. (_iOS_, _Android_, _BlackBerry 10_, _OSX_, _windows_)

* cordova.file.externalApplicationStorageDirectory - Application space on
external storage. (_Android_)

* cordova.file.externalDataDirectory - Where to put app-specific data files on
external storage. (_Android_)

* cordova.file.externalCacheDirectory - Application cache on external storage.
(_Android_)

* cordova.file.externalRootDirectory - External storage (SD card) root. (_Android_, _BlackBerry 10_)

* cordova.file.tempDirectory - Temp directory that the OS can clear at will. Do not
rely on the OS to clear this directory; your app should always remove files as
applicable. (_iOS_, _OSX_, _windows_)

* cordova.file.syncedDataDirectory - Holds app-specific files that should be synced
(e.g. to iCloud). (_iOS_, _windows_)

* cordova.file.documentsDirectory - Files private to the app, but that are meaningful
to other application (e.g. Office files). Note that for _OSX_ this is the user's ~/Documents directory. (_iOS_, _OSX_)

* cordova.file.sharedDirectory - Files globally available to all applications (_BlackBerry 10_)

File System Layouts

Although technically an implementation detail, it can be very useful to know how
the cordova.file.* properties map to physical paths on a real device.

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| Device Path | cordova.file.* | iosExtraFileSystems | r/w? | persistent? | OS clears | sync | private |
|:-----------------------------------------------|:----------------------------|:----------------------|:----:|:-----------:|:---------:|:----:|:-------:|
| /var/mobile/Applications// | applicationStorageDirectory | - | r | N/A | N/A | N/A | Yes |
|    appname.app/ | applicationDirectory | bundle | r | N/A | N/A | N/A | Yes |
|       www/ | - | - | r | N/A | N/A | N/A | Yes |
|    Documents/ | documentsDirectory | documents | r/w | Yes | No | Yes | Yes |
|       NoCloud/ | - | documents-nosync | r/w | Yes | No | No | Yes |
|    Library | - | library | r/w | Yes | No | Yes? | Yes |
|       NoCloud/ | dataDirectory | library-nosync | r/w | Yes | No | No | Yes |
|       Cloud/ | syncedDataDirectory | - | r/w | Yes | No | Yes | Yes |
|       Caches/ | cacheDirectory | cache | r/w | Yes | Yes\\\| No | Yes |
|    tmp/ | tempDirectory | - | r/w | No\\ | Yes\\\*| No | Yes |

\* Files persist across app restarts and upgrades, but this directory can
be cleared whenever the OS desires. Your app should be able to recreate any
content that might be deleted.

\\ Files may persist across app restarts, but do not rely on this behavior. Files
are not guaranteed to persist across updates. Your app should remove files from
this directory when it is applicable, as the OS does not guarantee when (or even
if) these files are removed.

\\\* The OS may clear the contents of this directory whenever it feels it is
necessary, but do not rely on this. You should clear this directory as
appropriate for your application.

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| Device Path | cordova.file.* | AndroidExtraFileSystems | r/w? | persistent? | OS clears | private |
|:------------------------------------------------|:----------------------------|:--------------------------|:----:|:-----------:|:---------:|:-------:|
| file:///android_asset/ | applicationDirectory | assets | r | N/A | N/A | Yes |
| /data/data// | applicationStorageDirectory | - | r/w | N/A | N/A | Yes |
|    cache | cacheDirectory | cache | r/w | Yes | Yes\* | Yes |
|    files | dataDirectory | files | r/w | Yes | No | Yes |
|       Documents | | documents | r/w | Yes | No | Yes |
| / | externalRootDirectory | sdcard | r/w | Yes | No | No |
|    Android/data// | externalApplicationStorageDirectory | - | r/w | Yes | No | No |
|       cache | externalCacheDirectory | cache-external | r/w | Yes | No\\| No |
|       files | externalDataDirectory | files-external | r/w | Yes | No | No |

\* The OS may periodically clear this directory, but do not rely on this behavior. Clear
the contents of this directory as appropriate for your application. Should a user
purge the cache manually, the contents of this directory are removed.

\\ The OS does not clear this directory automatically; you are responsible for managing
the contents yourself. Should the user purge the cache manually, the contents of the
directory are removed.

Note: If external storage can't be mounted, the cordova.file.external*
properties are null.

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| Device Path | cordova.file.* | iosExtraFileSystems | r/w? | OS clears | private |
|:-------------------------------------------------|:----------------------------|:----------------------|:----:|:---------:|:-------:|
| /Applications/.app/ | - | bundle | r | N/A | Yes |
|     Content/Resources/ | applicationDirectory | - | r | N/A | Yes |
| ~/Library/Application Support// | applicationStorageDirectory | - | r/w | No | Yes |
|     files/ | dataDirectory | - | r/w | No | Yes |
| ~/Documents/ | documentsDirectory | documents | r/w | No | No |
| ~/Library/Caches// | cacheDirectory | cache | r/w | No | Yes |
| /tmp/ | tempDirectory | - | r/w | Yes\* | Yes |
| / | rootDirectory | root | r/w | No\\ | No |

Note: This is the layout for non sandboxed applications. I you enable sandboxing, the applicationStorageDirectory will be below ~/Library/Containers//Data/Library/Application Support.

\* Files persist across app restarts and upgrades, but this directory can
be cleared whenever the OS desires. Your app should be able to recreate any
content that might be deleted. You should clear this directory as
appropriate for your application.

\\ Allows access to the entire file system. This is only available for non sandboxed apps.

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| Device Path | cordova.file.* | r/w? | persistent? | OS clears | private |
|:------------------------------------------------------|:----------------------------|:----:|:-----------:|:---------:|:-------:|
| ms-appdata:/// | applicationDirectory | r | N/A | N/A | Yes |
|    local/ | dataDirectory | r/w | Yes | No | Yes |
|    temp/ | cacheDirectory | r/w | No | Yes\* | Yes |
|    temp/ | tempDirectory | r/w | No | Yes\* | Yes |
|    roaming/ | syncedDataDirectory | r/w | Yes | No | Yes |

\* The OS may periodically clear this directory

Android Quirks

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There are multiple valid locations to store persistent files on an Android
device. See this page
for an extensive discussion of the various possibilities.

Previous versions of the plugin would choose the location of the temporary and
persistent files on startup, based on whether the device claimed that the SD
Card (or equivalent storage partition) was mounted. If the SD Card was mounted,
or if a large internal storage partition was available (such as on Nexus
devices,) then the persistent files would be stored in the root of that space.
This meant that all Cordova apps could see all of the files available on the
card.

If the SD card was not available, then previous versions would store data under
/data/data/, which isolates apps from each other, but may still
cause data to be shared between users.

It is now possible to choose whether to store files in the internal file
storage location, or using the previous logic, with a preference in your
application's config.xml file. To do this, add one of these two lines to
config.xml:

Without this line, the File plugin will use Internal as the default. If
a preference tag is present, and is not one of these values, the application
will not start.

If your application has previously been shipped to users, using an older (pre-
3.0.0) version of this plugin, and has stored files in the persistent filesystem,
then you should set the preference to Compatibility if your config.xml does not specify a location for the persistent filesystem. Switching the location to
"Internal" would mean that existing users who upgrade their application may be
unable to access their previously-stored files, depending on their device.

If your application is new, or has never previously stored files in the
persistent filesystem, then the Internal setting is generally recommended.

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Listing asset directories is really slow on Android. You can speed it up though, by
adding src/android/build-extras.gradle to the root of your android project (also
requires cordova-android@4.0.0 or greater).

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Marshmallow requires the apps to ask for permissions when reading/writing to external locations. By
default, your app has permission to write to
cordova.file.applicationStorageDirectory and cordova.file.externalApplicationStorageDirectory, and the plugin doesn't request permission
for these two directories unless external storage is not mounted. However due to a limitation, when external storage is not mounted, it would ask for
permission to write to cordova.file.externalApplicationStorageDirectory.

iOS Quirks

- cordova.file.applicationStorageDirectory is read-only; attempting to store
files within the root directory will fail. Use one of the other cordova.file.*
properties defined for iOS (only applicationDirectory and applicationStorageDirectory are
read-only).
- FileReader.readAsText(blob, encoding)
- The encoding parameter is not supported, and UTF-8 encoding is always in effect.

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There are two valid locations to store persistent files on an iOS device: the
Documents directory and the Library directory. Previous versions of the plugin
only ever stored persistent files in the Documents directory. This had the
side-effect of making all of an application's files visible in iTunes, which
was often unintended, especially for applications which handle lots of small
files, rather than producing complete documents for export, which is the
intended purpose of the directory.

It is now possible to choose whether to store files in the documents or library
directory, with a preference in your application's config.xml file. To do this,
add one of these two lines to config.xml:

Without this line, the File plugin will use Compatibility as the default. If
a preference tag is present, and is not one of these values, the application
will not start.

If your application has previously been shipped to users, using an older (pre-
1.0) version of this plugin, and has stored files in the persistent filesystem,
then you should set the preference to Compatibility. Switching the location to
Library would mean that existing users who upgrade their application would be
unable to access their previously-stored files.

If your application is new, or has never previously stored files in the
persistent filesystem, then the Library setting is generally recommended.

Browser Quirks

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- Each browser uses its own sandboxed filesystem. IE and Firefox use IndexedDB as a base.
All browsers use forward slash as directory separator in a path.
- Directory entries have to be created successively.
For example, the call fs.root.getDirectory('dir1/dir2', {create:true}, successCallback, errorCallback)
will fail if dir1 did not exist.
- The plugin requests user permission to use persistent storage at the application first start.
- Plugin supports cdvfile://localhost (local resources) only. I.e. external resources are not supported via cdvfile.
- The plugin does not follow "File System API 8.3 Naming restrictions".
- Blob and File' close function is not supported.
- FileSaver and BlobBuilder are not supported by this plugin and don't have stubs.
- The plugin does not support requestAllFileSystems. This function is also missing in the specifications.
- Entries in directory will not be removed if you use create: true flag for existing directory.
- Files created via constructor are not supported. You should use entry.file method instead.
- Each browser uses its own form for blob URL references.
- readAsDataURL function is supported, but the mediatype in Chrome depends on entry name extension,
mediatype in IE is always empty (which is the same as text-plain according the specification),
the mediatype in Firefox is always application/octet-stream.
For example, if the content is abcdefg then Firefox returns data:application/octet-stream;base64,YWJjZGVmZw==,
IE returns data:;base64,YWJjZGVmZw==, Chrome returns data:;base64,YWJjZGVmZw==.
- toInternalURL returns the path in the form file:///persistent/path/to/entry (Firefox, IE).
Chrome returns the path in the form cdvfile://localhost/persistent/file.

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- Chrome filesystem is not immediately ready after device ready event. As a workaround you can subscribe to filePluginIsReady event.
Example:
``javascript
window.addEventListener('filePluginIsReady', function(){ console.log('File plugin is ready');}, false);
`
You can use window.isFilePluginReadyRaised function to check whether event was already raised.
- window.requestFileSystem TEMPORARY and PERSISTENT filesystem quotas are not limited in Chrome.
- To increase persistent storage in Chrome you need to call window.initPersistentFileSystem method. Persistent storage quota is 5 MB by default.
- Chrome requires --allow-file-access-from-files run argument to support API via file:/// protocol.
- File object will be not changed if you use flag {create:true} when getting an existing Entry.
- events cancelable property is set to true in Chrome. This is contrary to the specification.
- toURL function in Chrome returns filesystem:-prefixed path depending on application host.
For example, filesystem:file:///persistent/somefile.txt, filesystem:http://localhost:8080/persistent/somefile.txt.
- toURL function result does not contain trailing slash in case of directory entry.
Chrome resolves directories with slash-trailed urls correctly though.
- resolveLocalFileSystemURL method requires the inbound url to have filesystem prefix. For example, url parameter for resolveLocalFileSystemURL
should be in the form filesystem:file:///persistent/somefile.txt as opposed to the form file:///persistent/somefile.txt in Android.
- Deprecated toNativeURL function is not supported and does not have a stub.
- setMetadata function is not stated in the specifications and not supported.
- INVALID_MODIFICATION_ERR (code: 9) is thrown instead of SYNTAX_ERR(code: 8) on requesting of a non-existant filesystem.
- INVALID_MODIFICATION_ERR (code: 9) is thrown instead of PATH_EXISTS_ERR(code: 12) on trying to exclusively create a file or directory, which already exists.
- INVALID_MODIFICATION_ERR (code: 9) is thrown instead of NO_MODIFICATION_ALLOWED_ERR(code: 6) on trying to call removeRecursively on the root file system.
- INVALID_MODIFICATION_ERR (code: 9) is thrown instead of NOT_FOUND_ERR(code: 1) on trying to moveTo directory that does not exist.

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- . and .. are not supported.
- IE does not support file:///-mode; only hosted mode is supported (http://localhost:xxxx).
- Firefox filesystem size is not limited but each 50MB extension will request a user permission.
IE10 allows up to 10mb of combined AppCache and IndexedDB used in implementation of filesystem without prompting,
once you hit that level you will be asked if you want to allow it to be increased up to a max of 250mb per site.
So size parameter for requestFileSystem function does not affect filesystem in Firefox and IE.
- readAsBinaryString function is not stated in the Specs and not supported in IE and does not have a stub.
- file.type is always null.
- You should not create entry using DirectoryEntry instance callback result which was deleted.
Otherwise, you will get a 'hanging entry'.
- Before you can read a file, which was just written you need to get a new instance of this file.
- setMetadata function, which is not stated in the Specs supports modificationTime field change only.
- copyTo and moveTo functions do not support directories.
- Directories metadata is not supported.
- Both Entry.remove and directoryEntry.removeRecursively don't fail when removing
non-empty directories - directories being removed are cleaned along with contents instead.
- abort and truncate functions are not supported.
- progress events are not fired. For example, this handler will be not executed:
`javascript
writer.onprogress = function() { /commands/ };
`

Upgrading Notes

In v1.0.0 of this plugin, the FileEntry and DirectoryEntry structures have changed,
to be more in line with the published specification.

Previous (pre-1.0.0) versions of the plugin stored the device-absolute-file-location
in the fullPath property of Entry objects. These paths would typically look like

/var/mobile/Applications//Documents/path/to/file (iOS)
/storage/emulated/0/path/to/file (Android)

These paths were also returned by the toURL() method of the Entry objects.

With v1.0.0, the fullPath attribute is the path to the file, _relative to the root of
the HTML filesystem_. So, the above paths would now both be represented by a FileEntry
object with a fullPath of

/path/to/file

If your application works with device-absolute-paths, and you previously retrieved those
paths through the fullPath property of Entry objects, then you should update your code
to use entry.toURL() instead.

For backwards compatibility, the resolveLocalFileSystemURL() method will accept a
device-absolute-path, and will return an Entry object corresponding to it, as long as that
file exists within either the TEMPORARY or PERSISTENT filesystems.

This has particularly been an issue with the File-Transfer plugin, which previously used
device-absolute-paths (and can still accept them). It has been updated to work correctly
with FileSystem URLs, so replacing entry.fullPath with entry.toURL() should resolve any
issues getting that plugin to work with files on the device.

In v1.1.0 the return value of toURL() was changed (see CB-6394)
to return an absolute 'file://' URL. wherever possible. To ensure a 'cdvfile:'-URL you can use toInternalURL() now.
This method will now return filesystem URLs of the form

cdvfile://localhost/persistent/path/to/file

which can be used to identify the file uniquely.

cdvfile protocol

Purpose

cdvfile://localhost/persistent|temporary|another-fs-root*/path/to/file can be used for platform-independent file paths.
cdvfile paths are supported by core plugins - for example you can download an mp3 file to cdvfile-path via cordova-plugin-file-transfer and play it via cordova-plugin-media.

__*Note__: See Where to Store Files, File System Layouts and Configuring the Plugin for more details about available fs roots.

To use cdvfile as a tag' src you can convert it to native path via toURL() method of the resolved fileEntry, which you can get via resolveLocalFileSystemURL - see examples below.

You can also use cdvfile:// paths directly in the DOM, for example:
`HTML

`

__Note__: This method requires following Content Security rules updates:
* Add cdvfile: scheme to Content-Security-Policy meta tag of the index page, e.g.:
- cdvfile: https://ssl.gstatic.com 'unsafe-eval'; style-src 'self' 'unsafe-inline'; media-src *">
Add to config.xml.

Converting cdvfile:// to native path

`javascript
resolveLocalFileSystemURL('cdvfile://localhost/temporary/path/to/file.mp4', function(entry) {
var nativePath = entry.toURL();
console.log('Native URI: ' + nativePath);
document.getElementById('video').src = nativePath;
`

Converting native path to cdvfile://

`javascript
resolveLocalFileSystemURL(nativePath, function(entry) {
console.log('cdvfile URI: ' + entry.toInternalURL());
`

Using cdvfile in core plugins

`javascript
fileTransfer.download(uri, 'cdvfile://localhost/temporary/path/to/file.mp3', function (entry) { ...
`
`javascript
var my_media = new Media('cdvfile://localhost/temporary/path/to/file.mp3', ...);
my_media.play();
`

#### cdvfile quirks
- Using cdvfile:// paths in the DOM is not supported on Windows platform (a path can be converted to native instead).




List of Error Codes and Meanings

When an error is thrown, one of the following codes will be used.

| Code | Constant |
|-----:|:------------------------------|
| 1 | NOT_FOUND_ERR |
| 2 | SECURITY_ERR |
| 3 | ABORT_ERR |
| 4 | NOT_READABLE_ERR |
| 5 | ENCODING_ERR |
| 6 | NO_MODIFICATION_ALLOWED_ERR |
| 7 | INVALID_STATE_ERR |
| 8 | SYNTAX_ERR |
| 9 | INVALID_MODIFICATION_ERR |
| 10 | QUOTA_EXCEEDED_ERR |
| 11 | TYPE_MISMATCH_ERR |
| 12 | PATH_EXISTS_ERR |

Configuring the Plugin (Optional)

The set of available filesystems can be configured per-platform. Both iOS and
Android recognize a tag in config.xml which names the
filesystems to be installed. By default, all file-system roots are enabled.




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* files: The application's internal file storage directory
* files-external: The application's external file storage directory
* sdcard: The global external file storage directory (this is the root of the SD card, if one is installed). You must have the android.permission.WRITE_EXTERNAL_STORAGE permission to use this.
* cache: The application's internal cache directory
* cache-external: The application's external cache directory
* assets: The application's bundle (read-only)
* root: The entire device filesystem
* applicationDirectory: ReadOnly with restricted access. Copying files in this directory is possible, but reading it directly results in 'file not found'.
Android also supports a special filesystem named "documents", which represents a "/Documents/" subdirectory within the "files" filesystem.

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* library: The application's Library directory
* documents: The application's Documents directory
* cache: The application's Cache directory
* bundle: The application's bundle; the location of the app itself on disk (read-only)
* root: The entire device filesystem

By default, the library and documents directories can be synced to iCloud. You can also request two additional filesystems, library-nosync and documents-nosync, which represent a special non-synced directory within the /Library or /Documents filesystem.

Sample: Create Files and Directories, Write, Read, and Append files

The File plugin allows you to do things like store files in a temporary or persistent storage location for your app (sandboxed storage) and to store files in other platform-dependent locations. The code snippets in this section demonstrate different tasks including:
* Accessing the file system
* Using cross-platform Cordova file URLs to store your files (see _Where to Store Files_ for more info)
* Creating files and directories
* Writing to files
* Reading files
* Appending files
* Display an image file

Create a persistent file

Before you use the File plugin APIs, you can get access to the file system using requestFileSystem. When you do this, you can request either persistent or temporary storage. Persistent storage will not be removed unless permission is granted by the user.

When you get file system access using requestFileSystem, access is granted for the sandboxed file system only (the sandbox limits access to the app itself), not for general access to any file system location on the device. (To access file system locations outside the sandboxed storage, use other methods such as window.resolveLocalFileSystemURL, which support platform-specific locations. For one example of this, see _Append a File_.)

Here is a request for persistent storage.

>Note When targeting WebView clients (instead of a browser) or native apps (Windows), you dont need to use requestQuota before using persistent storage.

`js
window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, function (fs) {

console.log('file system open: ' + fs.name);
fs.root.getFile("newPersistentFile.txt", { create: true, exclusive: false }, function (fileEntry) {

console.log("fileEntry is file?" + fileEntry.isFile.toString());
// fileEntry.name == 'someFile.txt'
// fileEntry.fullPath == '/someFile.txt'
writeFile(fileEntry, null);

}, onErrorCreateFile);

}, onErrorLoadFs);
`

The success callback receives FileSystem object (fs). Use fs.root to return a DirectoryEntry object, which you can use to create or get a file (by calling getFile). In this example, fs.root is a DirectoryEntry object that represents the persistent storage in the sandboxed file system.

The success callback for getFile receives a FileEntry object. You can use this to perform file write and file read operations.

Create a temporary file

Here is an example of a request for temporary storage. Temporary storage may be deleted by the operating system if the device runs low on memory.

`js
window.requestFileSystem(window.TEMPORARY, 5 1024 1024, function (fs) {

console.log('file system open: ' + fs.name);
createFile(fs.root, "newTempFile.txt", false);

}, onErrorLoadFs);
`
When you are using temporary storage, you can create or get the file by calling getFile. As in the persistent storage example, this will give you a FileEntry object that you can use for read or write operations.

`js
function createFile(dirEntry, fileName, isAppend) {
// Creates a new file or returns the file if it already exists.
dirEntry.getFile(fileName, {create: true, exclusive: false}, function(fileEntry) {

writeFile(fileEntry, null, isAppend);

}, onErrorCreateFile);

}
`

Write to a file

Once you have a FileEntry object, you can write to the file by calling createWriter, which returns a FileWriter object in the success callback. Call the write method of FileWriter to write to the file.

`js
function writeFile(fileEntry, dataObj) {
// Create a FileWriter object for our FileEntry (log.txt).
fileEntry.createWriter(function (fileWriter) {

fileWriter.onwriteend = function() {
console.log("Successful file write...");
readFile(fileEntry);
};

fileWriter.onerror = function (e) {
console.log("Failed file write: " + e.toString());
};

// If data object is not passed in,
// create a new Blob instead.
if (!dataObj) {
dataObj = new Blob(['some file data'], { type: 'text/plain' });
}

fileWriter.write(dataObj);
});
}
`

Read a file

You also need a FileEntry object to read an existing file. Use the file property of FileEntry to get the file reference, and then create a new FileReader object. You can use methods like readAsText to start the read operation. When the read operation is complete, this.result stores the result of the read operation.

`js
function readFile(fileEntry) {

fileEntry.file(function (file) {
var reader = new FileReader();

reader.onloadend = function() {
console.log("Successful file read: " + this.result);
displayFileData(fileEntry.fullPath + ": " + this.result);
};

reader.readAsText(file);

}, onErrorReadFile);
}
`

Append a file using alternative methods

Of course, you will often want to append existing files instead of creating new ones. Here is an example of that. This example shows another way that you can access the file system using window.resolveLocalFileSystemURL. In this example, pass the cross-platform Cordova file URL, cordova.file.dataDirectory, to the function. The success callback receives a DirectoryEntry object, which you can use to do things like create a file.

`js
window.resolveLocalFileSystemURL(cordova.file.dataDirectory, function (dirEntry) {
console.log('file system open: ' + dirEntry.name);
var isAppend = true;
createFile(dirEntry, "fileToAppend.txt", isAppend);
}, onErrorLoadFs);
`

In addition to this usage, you can use resolveLocalFileSystemURL to get access to some file system locations that are not part of the sandboxed storage system. See _Where to store Files_ for more information; many of these storage locations are platform-specific. You can also pass cross-platform file system locations to resolveLocalFileSystemURL using the _cdvfile protocol_.

For the append operation, there is nothing new in the createFile function that is called in the preceding code (see the preceding examples for the actual code). createFile calls writeFile. In writeFile, you check whether an append operation is requested.

Once you have a FileWriter object, call the seek method, and pass in the index value for the position where you want to write. In this example, you also test whether the file exists. After calling seek, then call the write method of FileWriter.

`js
function writeFile(fileEntry, dataObj, isAppend) {
// Create a FileWriter object for our FileEntry (log.txt).
fileEntry.createWriter(function (fileWriter) {

fileWriter.onwriteend = function() {
console.log("Successful file read...");
readFile(fileEntry);
};

fileWriter.onerror = function (e) {
console.log("Failed file read: " + e.toString());
};

// If we are appending data to file, go to the end of the file.
if (isAppend) {
try {
fileWriter.seek(fileWriter.length);
}
catch (e) {
console.log("file doesn't exist!");
}
}
fileWriter.write(dataObj);
});
}
`

Store an existing binary file

We already showed how to write to a file that you just created in the sandboxed file system. What if you need to get access to an existing file and convert that to something you can store on your device? In this example, you obtain a file using an xhr request, and then save it to the cache in the sandboxed file system.

Before you get the file, get a FileSystem reference using requestFileSystem. By passing window.TEMPORARY in the method call (same as before), the returned FileSystem object (fs) represents the cache in the sandboxed file system. Use fs.root to get the DirectoryEntry object that you need.

`js
window.requestFileSystem(window.TEMPORARY, 5 1024 1024, function (fs) {

console.log('file system open: ' + fs.name);
getSampleFile(fs.root);

}, onErrorLoadFs);
`

For completeness, here is the xhr request to get a Blob image. There is nothing Cordova-specific in this code, except that you forward the DirectoryEntry reference that you already obtained as an argument to the saveFile function. You will save the blob image and display it later after reading the file (to validate the operation).

`js
function getSampleFile(dirEntry) {

var xhr = new XMLHttpRequest();
xhr.open('GET', 'http://cordova.apache.org/static/img/cordova_bot.png', true);
xhr.responseType = 'blob';

xhr.onload = function() {
if (this.status == 200) {

var blob = new Blob([this.response], { type: 'image/png' });
saveFile(dirEntry, blob, "downloadedImage.png");
}
};
xhr.send();
}
`
>Note For Cordova 5 security, the preceding code requires that you add the domain name, http://cordova.apache.org, to the Content-Security-Policy element in index.html.

After getting the file, copy the contents to a new file. The current DirectoryEntry object is already associated with the app cache.

`js
function saveFile(dirEntry, fileData, fileName) {

dirEntry.getFile(fileName, { create: true, exclusive: false }, function (fileEntry) {

writeFile(fileEntry, fileData);

}, onErrorCreateFile);
}
`

In writeFile, you pass in the Blob object as the dataObj and you will save that in the new file.

`js
function writeFile(fileEntry, dataObj, isAppend) {

// Create a FileWriter object for our FileEntry (log.txt).
fileEntry.createWriter(function (fileWriter) {

fileWriter.onwriteend = function() {
console.log("Successful file write...");
if (dataObj.type == "image/png") {
readBinaryFile(fileEntry);
}
else {
readFile(fileEntry);
}
};

fileWriter.onerror = function(e) {
console.log("Failed file write: " + e.toString());
};

fileWriter.write(dataObj);
});
}
`

After writing to the file, read it and display it. You saved the image as binary data, so you can read it using FileReader.readAsArrayBuffer.

`js
function readBinaryFile(fileEntry) {

fileEntry.file(function (file) {
var reader = new FileReader();

reader.onloadend = function() {

console.log("Successful file write: " + this.result);
displayFileData(fileEntry.fullPath + ": " + this.result);

var blob = new Blob([new Uint8Array(this.result)], { type: "image/png" });
displayImage(blob);
};

reader.readAsArrayBuffer(file);

}, onErrorReadFile);
}
`

After reading the data, you can display the image using code like this. Use window.URL.createObjectURL to get a DOM string for the Blob image.

`js
function displayImage(blob) {

// Displays image if result is a valid DOM string for an image.
var elem = document.getElementById('imageFile');
// Note: Use window.URL.revokeObjectURL when finished with image.
elem.src = window.URL.createObjectURL(blob);
}
`

Display an image file

To display an image using a FileEntry, you can call the toURL method.

`js
function displayImageByFileURL(fileEntry) {
var elem = document.getElementById('imageFile');
elem.src = fileEntry.toURL();
}
`

If you are using some platform-specific URIs instead of a FileEntry and you want to display an image, you may need to include the main part of the URI in the Content-Security-Policy element in index.html. For example, on Windows 10, you can include ms-appdata: in your element. Here is an example.

`html

`

Create Directories

In the code here, you create directories in the root of the app storage location. You could use this code with any writable storage location (that is, any DirectoryEntry). Here, you write to the application cache (assuming that you used window.TEMPORARY to get your FileSystem object) by passing fs.root into this function.

This code creates the /NewDirInRoot/images folder in the application cache. For platform-specific values, look at _File System Layouts_.

`js
function createDirectory(rootDirEntry) {
rootDirEntry.getDirectory('NewDirInRoot', { create: true }, function (dirEntry) {
dirEntry.getDirectory('images', { create: true }, function (subDirEntry) {

createFile(subDirEntry, "fileInNewSubDir.txt");

}, onErrorGetDir);
}, onErrorGetDir);
}
``

When creating subfolders, you need to create each folder separately as shown in the preceding code.