Revision 45319 of LocalFileSystemSync

<p>The <code>LocalFileSystemSync</code> interface of the <a href="/en/DOM/File_API/File_System_API" title="en/DOM/File_API/File_System_APIB">File System API</a> gives you access to a sandboxed file system. It is intended to be used with <a href="/en/DOM/Worker" title="en/DOM/Worker"> WebWorkers</a>. The methods are implemented by <a href="/en/DOM/Worker" title="En/DOM/Worker">worker</a> objects.</p>
<h2>About this document</h2>
<p>This document was last updated on March 2, 2012 and follows the <a class="external" href="https://www.w3.org/TR/file-system-api/">W3C Specifications (Working Draft)</a> drafted on April 19, 2011.</p>
<h2>Basic concepts</h2>
<p>You can request access to a sandboxed file system by requesting <code>LocalFileSystemSync</code> object from within a web worker. The global methods in the <code>window</code> object <code>requestFileSystemSync()</code> and <code>resolveLocalFileSystemSyncURL()</code> methods are exposed to the Worker's global scope. Calling <code>window.requestFileSystemSync()</code> for creates new storage for your web app.</p>
<p>For more concepts, see the counterpart <a href="/en/DOM/File_API/File_System_API/LocalFileSystem#Basic_concepts" title="https://developer.mozilla.org/en/DOM/File_API/File_System_API/LocalFileSystem#Basic_concepts">article for the asynchronous API</a>.</p>
<h3>Example</h3>
<pre class="brush: js">//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*/);</pre>
<p>Because you are using a synchronous API, you don't need success and error callbacks.</p><h2>Method overview</h2>
<table class="standard-table"> <tbody> <tr> <td><code>FileSystemSync <a href="#requestFileSystemSync" title="#requestFileSystemSync">requestFileSystemSync</a> (in unsigned short <em>type</em>, in long long <em>size</em>) raises <a href="/en/DOM/File_API/File_System_API/FileException" title="en/DOM/File_API/File_System_API/FileException">FileException</a>; </code></td> </tr> <tr> <td><code>EntrySync <a href="#resolveLocalFileSystemSyncURL" title="resolveLocalFileSystemSyncURL">resolveLocalFileSystemSyncURL</a> (in DOMString <em>url</em>) raises <a href="/en/DOM/File_API/File_System_API/FileException" title="en/DOM/File_API/File_System_API/FileException">FileException</a>;</code></td> </tr> </tbody>
</table>
<h2>Constants</h2>
<table class="standard-table"> <thead> <tr> <th scope="col">Constant</th> <th scope="col">Value</th> <th scope="col">Description</th> </tr> </thead> <tbody> <tr> <td><a name="const_temporary"><code>TEMPORARY</code></a></td> <td><code>0</code></td> <td> <p>Transient storage that can be be removed by the browser at its discretion.</p> </td> </tr> <tr> <td><a name="const_persistent"><code>PERSISTENT</code></a></td> <td><code>1</code></td> <td>Storage that stays in the browser unless the user or the app expunges it.</td> </tr> </tbody>
</table>
<h2>Methods</h2>
<h3 name="requestFileSystem">requestFileSystemSync()</h3>
<p>Requests a file system where data should be stored. You access a sandboxed file system by requesting a <code>LocalFileSystemSync</code> object from within a web worker using this global method, <code>window.requestFileSystemSync()</code>.</p>
<pre><code>FileSystemSync</code> requestFileSystemSync(
  in unsigned short type, 
  in unsigned long long size  
);</pre>
<h5>Parameters</h5>
<dl> <dt>type</dt> <dd>The storage type of the file system. The values can be either <code><a href="#const_temporary">TEMPORARY</a></code> or <code><a href="#const_persistent">PERSISTENT</a></code>.</dd> <dt>size</dt> <dd>The storage space—in bytes—that you need for your app.</dd>
</dl>
<h5>Returns</h5>
<dl> <dt><code><a href="/en/DOM/File_API/File_System_API/FileSystemSync" title="en/DOM/File_API/File_System_API/FileSystemSync">FileSystemSync</a></code></dt> <dd>An object that represents the file system.</dd>
</dl>
<h5>Exceptions</h5>
<p>This method can raise an <a href="/en/DOM/File_API/File_System_API/FileException" title="en/DOM/File_API/File_System_API/FileException">FileException</a> with the following code:</p>
<dl> <dt><code>SECURITY_ERR</code></dt> <dd>The application does not have permission to access the file system interface. You cannot run from <code>file://</code>. For more details, see the <a href="/en/DOM/File_APIs/Filesystem/Basic_Concepts_About_the_Filesystem_API#You_cannot_run_your_app_from_file:.2F.2F" title="https://developer.mozilla.org/en/DOM/File_APIs/Filesystem/Basic_Concepts_About_the_Filesystem_API#You_cannot_run_your_app_from_file:.2F.2F">article on basic concepts</a>.</dd>
</dl>
<h3 name="resolveLocalFileSystemSyncURL()">resolveLocalFileSystemSyncURL()</h3>
<p>Allows the user to look up the <code>Entry</code> for a file or directory referred to by a local URL.</p>
<pre>void resolveLocalFileSystemURL(
  in DOMString url  
);</pre>
<h5>Parameter</h5>
<dl> <dt>url</dt> <dd>The URL of a local file in the file system.</dd>
</dl>
<h5>Returns</h5>
<dl> <dt><code><a href="/en/DOM/File_API/File_System_API/EntrySync" title="en/DOM/File_API/File_System_API/EntrySync">EntrySync</a></code></dt> <dd>An object that represents entries in the file system.</dd>
</dl>
<h5>Exceptions</h5>
<p>This method can raise an <a href="/en/DOM/File_API/File_System_API/FileException" title="en/DOM/File_API/File_System_API/FileException">FileException</a> with the following code:</p>
<dl> <dt><code>ENCODING_ERR</code></dt> <dd>The syntax of the URL was invalid.</dd> <dt><code>NOT_FOUND_ERR</code></dt> <dd>The URL was structurally correct, but refers to a resource that does not exist.</dd> <dt><code>SECURITY_ERR</code></dt> <dd>The application does not have permission to access the file system interface.</dd>
</dl>
<h2 name="Browser_Compatibility">Browser compatibility</h2>
<p>{{ CompatibilityTable() }}</p>
<div id="compat-desktop"> <table class="compat-table"> <tbody> <tr> <th>Feature</th> <th>Chrome</th> <th>Firefox (Gecko)</th> <th>Internet Explorer</th> <th>Opera</th> <th>Safari (WebKit)</th> </tr> <tr> <td>Basic support</td> <td>13{{ property_prefix("webkit") }}</td> <td>{{ CompatNo() }}</td> <td>{{ CompatNo() }}</td> <td>{{ CompatNo() }}</td> <td>{{ CompatNo() }}</td> </tr> </tbody> </table>
</div>
<div id="compat-mobile"> <table class="compat-table"> <tbody> <tr> <th>Feature</th> <th>Android</th> <th>Chrome for Android</th> <th>Firefox Mobile (Gecko)</th> <th>IE Phone</th> <th>Opera Mobile</th> <th>Safari Mobile</th> </tr> <tr> <td>Basic support</td> <td>{{ CompatNo() }}</td> <td>0.16{{ property_prefix("webkit") }}</td> <td>{{ CompatNo() }}</td> <td>{{ CompatNo() }}</td> <td>{{ CompatNo() }}</td> <td>{{ CompatNo() }}</td> </tr> </tbody> </table>
</div>
<h2>See also</h2>
<p>Specification:{{ spec("https://dev.w3.org/2009/dap/file-system/pub/FileSystem/", "File API: Directories and System Specification", "WD") }}</p>
<p>Reference: <a href="/en/DOM/File_API/File_System_API" title="en/DOM/File_API/File_System_API">File System API</a></p>
<p>Introduction: <a href="/en/DOM/File_APIs/Filesystem/Basic_Concepts_About_the_Filesystem_API" title="en/DOM/File_APIs/Filesystem/Basic_Concepts_About_the_Filesystem_API">Basic Concepts About the File System API</a></p>