initial commit

1 files changed, 145 insertions, 0 deletions

diff --git a/files/zh-cn/web/api/fetchobserver/index.html b/files/zh-cn/web/api/fetchobserver/index.html
new file mode 100644
index 0000000000..9bd7699388
--- /dev/null
+++ b/files/zh-cn/web/api/fetchobserver/index.html
@@ -0,0 +1,145 @@
+---
+title: FetchObserver
+slug: Web/API/FetchObserver
+translation_of: Web/API/FetchObserver
+---
+<div>{{draft}}{{APIRef("Fetch API")}}{{SeeCompatTable}}</div>
+
+<p><font><font>在</font></font><strong><code>FetchObserver</code></strong><font><font>接口</font></font><a href="https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API"><font><font>提取API</font></font></a><font><font>表示观察者对象，它允许您检索关于为获取请求的状态信息。</font></font></p>
+
+<h2 id="Properties">Properties</h2>
+
+<p><em><font><font>FetchObserver接口从其父接口继承属性</font></font><a href="https://developer.mozilla.org/en-US/docs/Web/API/EventTarget" title="EventTarget是一个由可以接收事件的对象实现的接口，并且可以为它们提供监听器。"><code>EventTarget</code></a><font><font>。</font></font></em></p>
+
+<dl>
+ <dt>{{domxref("FetchObserver.state")}} {{readonlyInline}}</dt>
+ <dd>Returns a <code>FetchState</code> enum value indicating the current state of the fetch request.</dd>
+</dl>
+
+<h3 id="Event_handlers">Event handlers</h3>
+
+<dl>
+ <dt>{{domxref("FetchObserver.onstatechange")}}</dt>
+ <dd>Invoked when a {{event("statechange_(cancellable_fetch)", "statechange")}} event fires, i.e. when the state of the fetch request changes.</dd>
+ <dt>{{domxref("FetchObserver.onrequestprogress")}}</dt>
+ <dd>Invoked when a {{event("requestprogress")}} event fires, i.e. when the request progresses.</dd>
+ <dt>{{domxref("FetchObserver.onresponseprogress")}}</dt>
+ <dd>Invoked when a {{event("responseprogress")}} event fires, i.e. when the download of the response progresses.</dd>
+</dl>
+
+<h2 id="Methods">Methods</h2>
+
+<p><em>The FetchSignal interface inherits methods from its parent interface, {{domxref("EventTarget")}}.</em></p>
+
+<h2 id="Examples">Examples</h2>
+
+<p>In the following snippet, we create a new {{domxref("FetchController")}} object, get its <code>signal</code>, and then give the signal to the <a href="/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch">fetch request</a> via the signal parameter of its <code>init</code> object so the controller can control it. Later on we specify an event listener on a cancel button so that when the button is clicked, we abort the fetch request using {{domxref("FetchController.abort()")}}.</p>
+
+<p>We also specify an observe property inside the fetch request <code>init</code> object — this contains a {{domxref("ObserverCallback")}} object, the sole purpose of which is to provide a callback function that runs when the fetch request runs. This returns a {{domxref("FetchObserver")}} object that can be used to retrieve information concerning the status of a fetch request.</p>
+
+<p>Here we use {{domxref("FetchController.responseprogress")}} and {{domxref("FetchController.onstatechange")}} event handlers to respectively fill up a progress bar as more of the reponse downloads, and to determine when the download has completed and display a message to let the user know.</p>
+
+<p><strong>Note that these event handlers are not yet supported anywhere.</strong></p>
+
+<pre class="brush: js">var controller = new FetchController();
+var signal = controller.signal;
+
+downloadBtn.addEventListener('click', function() {
+  fetch(url, {
+    signal,
+    observe(observer) {
+      observer.onresponseprogress = function(e) {
+        progress.max = e.total;
+        progress.value = e.loaded;
+      }
+
+      observer.onstatechange = function() {
+        if (observer.state = 'complete') {
+          reports.textContent = 'Download complete';
+        }
+      }
+    }
+  }).then( ... ) // do something with the response
+});
+
+cancelBtn.addEventListener('click', function() {
+  controller.abort();
+});</pre>
+
+<p>You can find a work-in-progress demo showing usage of <code>FetchObserver</code> on GitHub (see the <a href="https://github.com/mdn/fetch-examples/tree/master/fetch-signal-controller-observer">source code</a> and the <a href="https://mdn.github.io/fetch-examples/fetch-signal-controller-observer/">live example</a>).</p>
+
+<h2 id="Specifications">Specifications</h2>
+
+<p>Not part of a specification yet.</p>
+
+<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>Edge</th>
+   <th>Firefox (Gecko)</th>
+   <th>Internet Explorer</th>
+   <th>Opera</th>
+   <th>Safari (WebKit)</th>
+  </tr>
+  <tr>
+   <td>Basic support</td>
+   <td>
+    <p>{{CompatNo}}</p>
+   </td>
+   <td>{{CompatNo}}</td>
+   <td>{{CompatNo}}<sup>[1]</sup></td>
+   <td>{{CompatNo}}</td>
+   <td>
+    <p>{{CompatNo}}</p>
+   </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>Edge</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>{{CompatNo}}</td>
+   <td>{{CompatNo}}</td>
+   <td>{{CompatNo}}</td>
+   <td>{{CompatNo}}<sup>[1]</sup></td>
+   <td>{{CompatNo}}</td>
+   <td>{{CompatNo}}</td>
+   <td>{{CompatNo}}</td>
+   <td>{{CompatNo}}</td>
+  </tr>
+ </tbody>
+</table>
+</div>
+
+<p>[1] Hidden behind a preference in 55+ Nightly. In about:config, you need to create two new boolean prefs — <code>dom.fetchObserver.enabled</code> and <code>dom.fetchController.enabled</code> — and set the values of both to <code>true</code>.</p>
+
+<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>