Revision 1126637 of ConstrainDOMString

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

<p>The <strong><code>ConstrainDOMString</code></strong> dictionary is used to specify a constraint for a property whose value is a string. It allows you to specify one or more <code>exact</code> string values from which one must be the parameter's value, or a set of <code>ideal</code> values which should be used if possible. You can also specify a single string (or an array of strings) which the user agent will do its best to match once all more stringent constraints have been applied.</p>

<h2 id="Properties">Properties</h2>

<dl>
 <dt><code>exact</code></dt>
 <dd>Either a single {{domxref("DOMString")}} which must be the value of the property, or an array of <code>DOMString</code> objects one of which must be the property's value. If the property can't be set to one of the listed values, matching will fail.</dd>
 <dt><code>ideal</code></dt>
 <dd>Either a single {{domxref("DOMString")}} or an arrray of <code>DOMString</code>s specifying ideal values for the property. If possible, one of the listed values will be used, but if it's not possible, the user agent will use the closest possible match.</dd>
</dl>

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

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('Media Capture', '#idl-def-ConstrainDOMString', 'ConstrainDOMString')}}</td>
   <td>{{Spec2('Media Capture')}}</td>
   <td>Initial definition</td>
  </tr>
 </tbody>
</table>

<div class="note">
<p>Technically, <code>ConstrainDOMString</code> is actually based on an intermediary dictionary named <code>ConstrainDOMStringParameters</code>, which adds <code>exact</code> and <code>ideal</code> to {{domxref("DOMString")}}. However, for the sake of documentation clarity, the intermediate type (present only because of quirks in {{Glossary("WebIDL")}} syntax) is ignored here.</p>
</div>

<h2 id="Browser_compatibility">Browser compatibility</h2>

<div>{{CompatibilityTable}}</div>

<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>{{CompatVersionUnknown}}</td>
   <td>{{CompatGeckoDesktop(50)}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatNo}}</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 Phone</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>{{CompatNo}}</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("MediaTrackCapabilities")}}</li>
 <li>{{domxref("MediaTrackSupportedConstraints")}}</li>
</ul>