Revision 1131797 of MediaTrackConstraints.facingMode

<div>{{APIRef("Media Capture and Streams")}}</div>

<p>The {{domxref("MediaTrackConstraints")}} dictionary's <code><strong>facingMode</strong></code> property is a {{domxref("ConstrainDOMString")}} describing the requested or mandatory constraints placed upon the value of the {{domxref("MediaTrackSettings.facingMode", "facingMode")}} constrainable property.</p>

<p>If needed, you can determine whether or not this constraint is supported by checking the value of {{domxref("MediaTrackSupportedConstraints.facingMode")}} as returned by a call to {{domxref("MediaDevices.getSupportedConstraints()")}}. However, typically this is unnecessary since browsers will simply ignore any constraints they're unfamiliar with.</p>

<h2 id="Syntax">Syntax</h2>

<pre class="syntaxbox">
var <em>constraintsObject</em> = { facingMode: <em>constraint</em> };

<em>constraintsObject</em>.facingMode = <em>constraint</em>;
</pre>

<h3 id="Value">Value</h3>

<p>An object based on {{domxref("ConstrainDOMString")}} specifying one or more acceptable, ideal, and/or exact (mandatory) facing modes are acceptable for a video track.</p>

<p>An <code>exact</code> value in this case indicates that the specified facing mode is specifically required; for example:</p>

<pre class="brush: js">
var constraints = {
  facingMode: { exact: "user" }
};</pre>

<p>This indicates that only a user-facing camera is acceptable; if there is no user-facing camera, or the user declines permission to use that camera, the media request will fail.</p>

<h2 id="Example" name="Example">Example</h2>

<p>See {{SectionOnPage("/en-US/docs/Web/API/Media_Streams_API/Constraints", "Example: Constraint exerciser")}} for an example.</p>

<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('Media Capture', '#widl-MediaTrackConstraints-facingMode', 'facingMode') }}</td>
   <td>{{ Spec2('Media Capture') }}</td>
   <td>Initial specification.</td>
  </tr>
 </tbody>
</table>

<h2 id="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</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{ CompatGeckoDesktop(50) }}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Android Webview</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
   <th>Chrome for Android</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{ CompatGeckoMobile(50) }}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

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

<ul>
 <li><a href="/en-US/docs/Web/API/Media_Streams_API">Media Capture and Streams API</a></li>
 <li><a href="/en-US/docs/Web/API/Media_Streams_API/Constraints">Capabilities, constraints, and settings</a></li>
 <li>{{domxref("MediaTrackConstraints")}}</li>
 <li>{{domxref("MediaDevices.getSupportedConstraints()")}}</li>
 <li>{{domxref("MediaTrackSupportedConstraints")}}</li>
 <li>{{domxref("MediaStreamTrack")}}</li>
</ul>