Revision 1072250 of Request.mode

<div>{{APIRef("Fetch")}}{{SeeCompatTable}}</div>

<p>The <strong><code>mode</code></strong> read-only property of the {{domxref("Request")}} interface contains the mode of the request (e.g., <code>cors</code>, <code>no-cors</code>, <code>cors-with-forced-preflight</code>, <code>same-origin</code>, or <code>navigate</code>.) This is used to determine if cross-origin requests lead to valid responses, and which properties of the response are readable:</p>

<ul>
 <li><code>same-origin</code> — If a request is made to another origin with this mode set, the result is simply an error. You could use this to ensure that a request is always being made to your origin.</li>
 <li><code>no-cors</code> — Prevents the method from being anything other than <code>HEAD</code>, <code>GET</code> or <code>POST</code>. If any ServiceWorkers intercept these requests, they may not add or override any headers except for <a href="https://fetch.spec.whatwg.org/#simple-header">these</a>. In addition, JavaScript may not access any properties of the resulting {{domxref("Response")}}. This ensures that ServiceWorkers do not affect the semantics of the Web and prevents security and privacy issues arising from leaking data across domains.</li>
 <li><code>cors</code> — Allows cross-origin requests, for example to access various APIs offered by 3rd party vendors. These are expected to adhere to the <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS">CORS protocol</a>. Only a <a href="https://fetch.spec.whatwg.org/#concept-filtered-response-cors">limited set</a> of headers are exposed in the {{domxref("Response")}}, but the body is readable.</li>
 <li><code>navigate</code> — A mode for supporting navigation. The <code>navigate</code> value is intended to be used only by HTML navigation. A navigate request is created only while navigating between documents.</li>
</ul>

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

<pre class="syntaxbox">
var <var>myMode</var> = <var>request</var>.mode;</pre>

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

<p>A {{domxref("RequestMode")}} value.</p>

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

<p>In the following snippet, we create a new request using the {{domxref("Request.Request()")}} constructor (for an image file in the same directory as the script), then save the request mode in a variable:</p>

<pre class="brush: js" data-number="">
var myRequest = new Request('flowers.jpg');
var myMode = myRequest.mode; // returns "cors" by default</pre>

<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('Fetch','#dom-request-mode', 'mode')}}</td>
   <td>{{Spec2('Fetch')}}</td>
   <td>Initial definition</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 (WebKit)</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatChrome(42.0)}}</td>
   <td>{{CompatGeckoDesktop(39)}}</td>
   <td>{{CompatNo}}</td>
   <td>
    <p>29<br />
     28<sup>[1]</sup></p>
   </td>
   <td>{{CompatNo}}</td>
  </tr>
  <tr>
   <td><code>navigate</code> mode</td>
   <td>{{CompatChrome(49.0)}}</td>
   <td>{{CompatGeckoDesktop(46)}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatUnknown}}</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>Android Webview</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Firefox OS (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>{{CompatNo}}</td>
   <td>{{CompatChrome(49.0)}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatChrome(49.0)}}</td>
  </tr>
  <tr>
   <td><code>navigate</code> mode</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatChrome(49.0)}}</td>
  </tr>
 </tbody>
</table>
</div>

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

<ul>
 <li><a href="/en-US/docs/Web/API/ServiceWorker_API">ServiceWorker API</a></li>
 <li><a href="/en-US/docs/Web/HTTP/Access_control_CORS">HTTP access control (CORS)</a></li>
 <li><a href="/en-US/docs/Web/HTTP">HTTP</a></li>
</ul>