Revision 1125133 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="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="Methods">Methods</h2>

<dl>
 <dt>{{domxref("FileSystemFileEntry.createWriter", "createWriter()")}}</dt>
 <dd>Creates a new {{domxref("FileWriter")}} object which allows writing to the file represented by the file system entry.</dd>
 <dt>{{domxref("FileSystemFileEntry.file", "file()")}}</dt>
 <dd>Creates a new {{domxref("File")}} object which can be used to read the file.</dd>
</dl>

<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")}} object 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();
      bb.append('Meow');
      
      fileWriter.write(bb.getBlob('text/plain'));
    }, errorHandler);

  }, errorHandler);

}

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

<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>Microsoft Edge</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>{{CompatVersionUnknown}}<sup>[2]</sup></td>
   <td>{{ CompatNo }}</td>
   <td>{{ CompatNo }}</td>
  </tr>
  <tr>
   <td><code>createWriter()</code></td>
   <td>13 {{ property_prefix("webkit") }}</td>
   <td>{{ CompatNo }}<sup>[1]</sup></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&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>
  <tr>
   <td><code>createWriter()</code></td>
   <td>{{ CompatNo }}</td>
   <td>0.16{{ property_prefix("webkit") }}</td>
   <td>{{ CompatNo }}<sup>[1]</sup></td>
   <td>{{ CompatNo }}</td>
   <td>{{ CompatNo }}</td>
   <td>{{ CompatNo }}</td>
  </tr>
 </tbody>
</table>
</div>

<p>[1] While the <code>createWriter()</code> method exists in Firefox 50, it is not supported, and immediately reports an <code>NS_ERROR_DOM_SECURITY_ERR</code> error to the error callback.</p>

<p>[2] Microsoft Edge implements this interface as part of the <code>WebKitEntry</code> interface, which is its name for {{domxref("FileSystemEntry")}}.</p>

<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>