LocalFileSystemSync

Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The LocalFileSystemSync interface of the File System API gives you access to a sandboxed file system. It is intended to be used with WebWorkers. The methods are implemented by worker objects.

About this document

This document was last updated on March 2, 2012 and follows the W3C Specifications (Working Draft) drafted on April 19, 2011.

This specification is more or less abandonned, failing to get significant traction.

Basic concepts

You can request access to a sandboxed file system by requesting LocalFileSystemSync object from within a web worker. The global methods in the window object requestFileSystemSync() and resolveLocalFileSystemSyncURL() methods are exposed to the Worker's global scope. Calling window.requestFileSystemSync() for creates new storage for your web app.

For more concepts, see the counterpart article for the asynchronous API.

Example

//Taking care of the browser-specific prefix
window.requestFileSystemSync  = window.requestFileSystemSync || window.webkitRequestFileSystemSync;

// The first parameter defines the type of storage: persistent or temporary
// Next, set the size of space needed (in bytes)
// initFs is the success callback
// And the last one is the error callback
// for denial of access and other errors. 

var fs = requestFileSystemSync(TEMPORARY, 1024*1024 /*1MB*/);

Because you are using a synchronous API, you don't need success and error callbacks.

Method overview

FileSystemSync requestFileSystemSync (in unsigned short type, in long long size) raises FileException;
EntrySync resolveLocalFileSystemSyncURL (in DOMString url) raises FileException;

Constants

Constant Value Description
TEMPORARY 0

Transient storage that can be be removed by the browser at its discretion.

PERSISTENT 1 Storage that stays in the browser unless the user or the app expunges it.

Methods

requestFileSystemSync()

Requests a file system where data should be stored. You access a sandboxed file system by requesting a LocalFileSystemSync object from within a web worker using this global method, window.requestFileSystemSync(). [ RESEARCH ]

FileSystemSync requestFileSystemSync(
  in unsigned short type, 
  in unsigned long long size  
);
Parameters
type
The storage type of the file system. The values can be either TEMPORARY or PERSISTENT.
size
The storage space—in bytes—that you need for your app.
Returns
FileSystemSync
An object that represents the file system.
Exceptions

This method can raise an FileException with the following code:

Exception Description
SECURITY_ERROR The application does not have permission to access the file system interface. For example, you cannot run from file://. For more details, see the article on basic concepts.

resolveLocalFileSystemSyncURL()

Allows the user to look up the Entry for a file or directory referred to by a local URL.

void resolveLocalFileSystemURL(
  in DOMString url  
);
Parameter
url
The URL of a local file in the file system.
Returns
EntrySync
An object that represents entries in the file system.
Exceptions

This method can raise a FileException with the following codes:

Exception Description
ENCODING_ERR The syntax of the URL was invalid.
NOT_FOUND_ERR The URL was structurally correct, but refers to a resource that does not exist.
SECURITY_ERR The application does not have permission to access the file system interface.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic support
Non-standard
Chrome Full support 13
Prefixed
Full support 13
Prefixed
Prefixed Implemented with the vendor prefix: webkit
Edge ? Firefox No support NoIE No support NoOpera No support NoSafari No support NoWebView Android Full support Yes
Prefixed
Full support Yes
Prefixed
Prefixed Implemented with the vendor prefix: webkit
Chrome Android Full support Yes
Prefixed
Full support Yes
Prefixed
Prefixed Implemented with the vendor prefix: webkit
Edge Mobile ? Firefox Android No support NoOpera Android No support NoSafari iOS No support NoSamsung Internet Android ?
requestFileSystemSync
Non-standard
Chrome Full support 13Edge ? Firefox No support NoIE No support NoOpera No support NoSafari No support NoWebView Android Full support YesChrome Android Full support YesEdge Mobile ? Firefox Android No support NoOpera Android No support NoSafari iOS No support NoSamsung Internet Android ?
resolveLocalFileSystemSyncURL
Non-standard
Chrome Full support 13Edge ? Firefox No support NoIE No support NoOpera No support NoSafari No support NoWebView Android Full support YesChrome Android Full support YesEdge Mobile ? Firefox Android No support NoOpera Android No support NoSafari iOS No support NoSamsung Internet Android ?

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
Non-standard. Expect poor cross-browser support.
Non-standard. Expect poor cross-browser support.
Requires a vendor prefix or different name for use.
Requires a vendor prefix or different name for use.

See also

Specification:File API: Directories and System SpecificationWD

Reference: File System API

Introduction: Basic Concepts About the File System API

Document Tags and Contributors

Contributors to this page: fscholz, kscarfone, teoli, Sheppy, grendel
Last updated by: fscholz,