Revision 1119671 of FileSystemFileEntry

<div>{{APIRef("File System API")}}{{Non-standard_header}}</div>

<p>The <strong><code>FileSystemFileEntry</code></strong> interface of the <a href="/en/DOM/File_API/File_System_API" title="en/DOM/File_API/File_System_API">File System API</a> represents a file in a file system. It offers properties describing the file's attributes, as well as methods for creating a {{domxref("FileWriter")}} object to write to the file or a {{domxref("File")}} object to read the file.</p>

<div class="note">
<p>Because this is a non-standard API, whose specification is not currently on a standards track, it's important to keep in mind that not all browsers implement it, and those that do may implement only small portions of it. Check the {{anch("Browser compatibility")}} section for details.</p>
</div>

<h2 id="basic_concepts" name="basic_concepts">Basic concepts</h2>

<p>To write content to file, create a {{domxref("FileWriter")}} object by calling {{domxref("FileSystemFileEntry.createWriter", "createWriter()")}}. To read a file, obtain a {{domxref("File")}} oject representing its contents by calling {{domxref("FileSystemFileEntry.file", "file()")}}.</p>

<h3 id="example" name="example">Example</h3>

<p>The following code creates an empty file called "log.txt" (if it doesn't exist) and fills it with the text 'Meow'. Inside the success callback, event handlers are set up for <code>error</code> and <code>writeend</code> events. The text data is written to the file by creating a blob, appending text to it, and passing the blob to <code>FileWriter.write()</code>.</p>

<pre class="brush: js">
function onInitFs(fs) {

  fs.root.getFile('log.txt', {create: true}, function(fileEntry) {

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

      fileWriter.onwriteend = function(e) {
        console.log('Write completed.');
      };

      fileWriter.onerror = function(e) {
        console.log('Write failed: ' + e.toString());
      };

      // Create a new Blob and write it to log.txt.
      var bb = new BlobBuilder(); 
     // Note: window.WebKitBlobBuilder.
      bb.append('Meow');
      
      fileWriter.write(bb.getBlob('text/plain'));

    }, errorHandler);

  }, errorHandler);

}

window.requestFileSystem(window.TEMPORARY, 1024*1024, onInitFs, errorHandler);</pre>

<h2 id="Properties" style="line-height: 30px; font-size: 2.14285714285714rem;">Properties</h2>

<p><em>Inherits the properties of its parent interface, {{domxref("FileSystemEntry")}}, but has no properties unique to this interface.</em></p>

<h2 id="Method_overview">Method overview</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <td><code>void <a href="#createReader" title="#createWriter">createWriter</a> (FileWriterCallback successCallback, optional ErrorCallback errorCallback);</code></td>
  </tr>
  <tr>
   <td><code>void <a href="#File" title="#file">file</a> (FileCallback successCallback, optional ErrorCallback errorCallback)</code>;</td>
  </tr>
 </tbody>
</table>

<h2 id="Methods">Methods</h2>

<h3 id="createWriter" name="createWriter">createWriter()</h3>

<p>Creates a new <code>FileWriter</code> object associated with the selected file.</p>

<pre>
void createWriter (
 in FileWriterCallback successCallback, optional ErrorCallback errorCallback
);</pre>

<h5 id="Parameters">Parameters</h5>

<dl>
 <dt>successCallback</dt>
 <dd>A callback that is called with the new <code>FileWriter</code> object.</dd>
 <dt>errorCallback</dt>
 <dd>A callback that is called when errors happen.</dd>
</dl>

<h5 id="Returns">Returns</h5>

<dl>
 <dt><code>void</code></dt>
</dl>

<h3 id="File" name="File">file()</h3>

<p>Returns a <a href="/en/docs/Web/API/File"><code>File</code></a> object associated with the selected file. You can use this to read the file's content.</p>

<pre>
void file (
  <em>FileCallback successCallback, optional ErrorCallback errorCallback</em>
);</pre>

<h5 id="Parameters_2">Parameters</h5>

<dl>
 <dt>successCallback</dt>
 <dd>A callback that is called with the new <code>File</code>.</dd>
 <dt>errorCallback</dt>
 <dd>A callback that is called when errors happen.</dd>
</dl>

<h5 id="Returns_2">Returns</h5>

<dl>
 <dt><code>void</code></dt>
</dl>

<h2 id="Specifications">Specifications</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{SpecName('File System API')}}</td>
   <td>{{Spec2('File System API')}}</td>
   <td>Draft of proposed API</td>
  </tr>
 </tbody>
</table>

<p>This API has no official W3C or WHATWG specification.</p>

<h2 id="Browser_compatibility" 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>{{ CompatGeckoDesktop(50) }}</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&nbsp;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>{{CompatGeckoMobile(50)}}</td>
   <td>{{ CompatNo }}</td>
   <td>{{ CompatNo }}</td>
   <td>{{ CompatNo }}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="See_also">See also</h2>

<ul>
 <li><a href="/en-US/docs/Web/API/File_and_Directory_Entries_API">File and Directory Entries API</a></li>
 <li><a href="/en-US/docs/Web/API/File_and_Directory_Entries_API/Introduction">Introduction to the File System API</a></li>
</ul>