---
title: Geolocation.watchPosition()
slug: Web/API/Geolocation/watchPosition
translation_of: Web/API/Geolocation/watchPosition
---
<p>{{ APIref("Geolocation API") }}</p>

<p><strong><code>Geolocation.watchPosition()</code></strong> 這個方法是用來註冊一個處理的函式，當使用者的裝置位置更新時，這個函式所傳入的回呼函式(callback function) 就會自動被呼叫。你也可以選擇性的定義錯誤時哪些錯誤回呼函式(error callback function) 需要被呼叫。</p>

<p>這個函式將回傳一組 ID 編號，此編號搭配 {{domxref("Geolocation.clearWatch()")}} 函式，即可停止更新使用者的位置。</p>

<h2 id="語法">語法</h2>

<pre class="syntaxbox"><em>id</em> = navigator.geolocation.watchPosition(<em>success[</em>, <em>error[</em>, <em>options]]</em>)</pre>

<h3 id="參數">參數</h3>

<dl>
 <dt><em>success</em></dt>
 <dd>一個回呼函式(callback function) 會被傳入一個 {{domxref("Position")}} 的物件。</dd>
 <dt><em>error</em> {{optional_inline}}</dt>
 <dd>一個選擇性的錯誤回呼函式(callback function)，會被傳入一個{{domxref("PositionError")}} 的物件。</dd>
 <dt><em>options</em> {{optional_inline}}</dt>
 <dd>一個選擇性 {{domxref("PositionOptions")}} 的物件。</dd>
</dl>

<h2 id="範例">範例</h2>

<pre class="brush: js">var id, target, options;

function success(pos) {
  var crd = pos.coords;

  if (target.latitude === crd.latitude &amp;&amp; target.longitude === crd.longitude) {
    console.log('Congratulations, you reached the target');
    navigator.geolocation.clearWatch(id);
  }
}

function error(err) {
  console.warn('ERROR(' + err.code + '): ' + err.message);
}

target = {
  latitude : 0,
  longitude: 0
};

options = {
  enableHighAccuracy: false,
  timeout: 5000,
  maximumAge: 0
};

id = navigator.geolocation.watchPosition(success, error, options);
</pre>

<h2 id="備註">備註</h2>

<p>如果你的應用程式是跑在 firefox OS上，請參考 <a href="/en-US/docs/Web/API/Geolocation/navigator.requestWakeLock()">geolocation wake lock</a>，此方法可以讓你的程式在背景或螢幕關上時也能持續收到位置更新。</p>

<h2 id="規格">規格</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('Geolocation', '#watch-position', 'Geolocation.watchPosition()')}}</td>
   <td>{{Spec2('Geolocation')}}</td>
   <td>Initial specification.</td>
  </tr>
 </tbody>
</table>

<h2 id="瀏覽器的相容性">瀏覽器的相容性</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>5</td>
   <td>{{CompatGeckoDesktop("1.9.1")}}</td>
   <td>9</td>
   <td>10.60<br>
    Removed in 15.0<br>
    Reintroduced in 16.0</td>
   <td>5</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 Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatUnknown()}}</td>
   <td>{{CompatUnknown()}}</td>
   <td>{{CompatGeckoMobile("4")}}</td>
   <td>{{CompatUnknown()}}</td>
   <td>10.60</td>
   <td>{{CompatUnknown()}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="請參考">請參考</h2>

<ul>
 <li><a href="/en-US/docs/Web/API/Geolocation/navigator.requestWakeLock()">geolocation wake lock</a></li>
 <li><a href="/en-US/docs/WebAPI/Using_geolocation" title="/en-US/docs/WebAPI/Using_geolocation">Using geolocation</a></li>
 <li>這個介面屬於{{domxref("Geolocation")}}. 並且存取他的方式為{{domxref("NavigatorGeolocation.geolocation")}}.</li>
 <li>相反的操作: {{domxref("Geolocation.clearWatch()")}}</li>
 <li>類似的方法: {{domxref("Geolocation.getCurrentPosition()")}}</li>
</ul>