path: root/files/zh-tw/web/api/notifications_api/using_the_notifications_api/index.html

---
title: 使用 Web Notifications
slug: Web/API/Notifications_API/Using_the_Notifications_API
translation_of: Web/API/Notifications_API/Using_the_Notifications_API
---
<p>{{SeeCompatTable}}</p>

<h2 id="摘要">摘要</h2>

<p>Web Notifications API 可將通知傳送至頁面以外的系統層級並顯示通知。因此即使 Web Apps 處於閒置狀態，亦可傳送資訊予使用者。絕佳範例之一，就是在使用其他 Apps 時，Web Mail App 同樣可通知使用者已接收到新郵件。</p>

<h2 id="要求權限">要求權限</h2>

<h3 id="網頁內容">網頁內容</h3>

<p>在 Apps 傳送通知之前，使用者必須先許可 Apps 的動作。只要 APIs 嘗試予網頁之外的東西互動，均必須先獲得使用者的授權。如此可避免濫發通知而影響使用經驗。</p>

<p>透過 <a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification.permission" title="The permission property indicates the current permission granted by the user about web notification for the current application."><code>Notification.permission</code></a> 唯讀屬性，要傳送通知的 Apps 將檢查目前的授權狀態。此屬性共有 3 組參數：</p>

<ul>
 <li><code>default：</code>使用者尚未給予任何權限 (因此不會顯示任何通知)</li>
 <li><code>granted</code>：使用者允許接收到 Apps 的通知</li>
 <li><code>denied</code><code>：使用者拒絕接收 </code>Apps 的通知</li>
</ul>

<div class="note">
<p><strong>注意：</strong>Chrome 與 Safari 尚未建構 <code>permission</code> 屬性。</p>
</div>

<p>若使用者尚未給予權限，則 Apps 必須透過 <a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification.requestPermission" title="The requestPermission static method is used to ask the user for his permission to display a Notification to him."><code>Notification.requestPermission()</code></a> 函式讓使用者選擇，接著由此函式接收 1 組回呼 (Callback) 函式作為參數；而該回呼函式則提供使用者是否授權的資訊。</p>

<p>以下為啟動 Apps 時要求權限的常用範例：</p>

<pre class="brush: js">window.addEventListener('load', function () {
  Notification.requestPermission(function (status) {
    // This allows to use Notification.permission with Chrome/Safari
    if (Notification.permission !== status) {
      Notification.permission = status;
    }
  });
});</pre>

<div class="note">
<p><strong>注意：</strong>Chrome 不允許於載入事件中呼叫 <a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification.requestPermission" title="The requestPermission static method is used to ask the user for his permission to display a Notification to him."><code>Notification.requestPermission()</code></a> (參閱 <a href="https://code.google.com/p/chromium/issues/detail?id=274284" title="https://code.google.com/p/chromium/issues/detail?id=274284">issue 274284</a>)。</p>
</div>

<h3 id="已安裝的_Apps">已安裝的 Apps</h3>

<p>在安裝 Apps 之後，若於 <a href="https://developer.mozilla.org/zh-TW/docs/%E6%87%89%E7%94%A8%E7%A8%8B%E5%BC%8F/Manifest-840092-dup" title="/en-US/docs/Web/Apps/Manifest">Apps 的 manifest 檔案</a>中直接添加權限，即可省去再次向使用者要求權限的動作。</p>

<pre class="brush: json">permissions: {
  "desktop-notification": {
    "description: "Allows to display notifications on the user's desktop.
  }
}</pre>

<h2 id="建立通知">建立通知</h2>

<p>透過 <a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification" title="The Notification object is used to configure and display desktop notifications to the user."><code>Notification</code></a> 建構子 (Constructor) 即可建立通知。此建構子包含 1 組標題，可於通知內顯示；另有如 <a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification.icon" title="The icon property indicates the URL of the icon to use with the notification."><code>icon</code></a> 或文字 <a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification.body" title="The body property represents the text content of the body of the notification."><code>body</code></a><code> 等</code>數個選項，可強化通知的內容。</p>

<p>在建立實體 (Instantiated) 之後，就會儘快顯示通知。若要追蹤通知的目前狀態，必須在 <a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification" title="The Notification object is used to configure and display desktop notifications to the user."><code>Notification</code></a> 的實體階層觸發 4 個事件：</p>

<ul>
 <li><a href="https://developer.mozilla.org/en-US/docs/Web/Reference/Events/show" title="/en-US/docs/Web/Reference/Events/show">show</a>：對使用者顯示通知之後，隨即觸發</li>
 <li><a href="https://developer.mozilla.org/en-US/docs/Web/Reference/Events/click" title="/en-US/docs/Web/Reference/Events/click">click</a>：使用者點擊通知之後，隨即觸發</li>
 <li><a href="https://developer.mozilla.org/en-US/docs/Web/Reference/Events/close" title="/en-US/docs/Web/Reference/Events/close">close</a>：關閉通知之後，隨即觸發</li>
 <li><a href="https://developer.mozilla.org/en-US/docs/Web/Reference/Events/error" title="/en-US/docs/Web/Reference/Events/error">error</a>：通知發生任何錯誤 (大多數是因為某種情況而未顯示通知)，隨即觸發</li>
</ul>

<p>而透過 <a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification.onshow" title="Specifies an event listener to receive show events. These events occur when a Notification is displayed."><code>onshow</code></a>、<a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification.onclick" title="Specifies an event listener to receive click events. These events occur when the user clicks on a displayed Notification."><code>onclick</code></a>、<a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification.onclose" title="Specifies an event listener to receive close events. These events occur when a Notification is closed."><code>onclose</code></a>，或 <a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification.onerror" title="Specifies an event listener to receive error events. These events occur when something goes wrong with a Notification (in many cases an error prevented the notification from being displayed)."><code>onerror</code></a> 等事件處理器 (Event handler)，即可追蹤這些事件。由於 <a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification" title="The Notification object is used to configure and display desktop notifications to the user."><code>Notification</code></a> 是繼承 <a href="https://developer.mozilla.org/en-US/docs/Web/API/EventTarget" title="EventTarget is a DOM interface implemented by objects that can receive DOM events and have listeners for them."><code>EventTarget</code></a> 而來，因此亦可使用 <a href="https://developer.mozilla.org/en-US/docs/Web/API/EventTarget.addEventListener" title="addEventListener() registers the specified listener on the EventTarget it's called on. The event target may be an Element in a document, the Document itself, a Window, or any other object that supports events (such as XMLHttpRequest)."><code>addEventListener()</code></a> 函式。</p>

<div class="note">
<p><strong>注意：</strong>Firefox 與 Safari 並未遵守 close 事件的規格。此規格雖然規定「僅限使用者能關閉通知」，但 Firefox 與 Safari 卻可於數分鐘後自動關閉通知。因此不一定是由使用者關閉通知。</p>

<p>此規格並明確規定「應透過 <a href="https://developer.mozilla.org/en-US/docs/Web/API/Notification.close" title="The close method is used to close a Notification that has been displayed."><code>Notification.close()</code></a> 函式，於應用程式層級完成自動關閉通知」。範例程式碼如下：</p>

<pre class="brush: js">var n = new Notification("Hi!");
n.onshow = function () {
  setTimeout(n.close, 5000);
}
</pre>
</div>

<h3 id="簡易範例">簡易範例</h3>

<p>先假設下列基本 HTML：</p>

<pre class="brush: html">&lt;button&gt;Notify me!&lt;/button&gt;</pre>

<p>則能以這種方法處理通知：</p>

<pre class="brush: js">window.addEventListener('load', function () {
  // At first, let's check if we have permission for notification
  // If not, let's ask for it
  if (Notification &amp;&amp; Notification.permission !== "granted") {
    Notification.requestPermission(function (status) {
      if (Notification.permission !== status) {
        Notification.permission = status;
      }
    });
  }
  var button = document.getElementsByTagName('button')[0];
  button.addEventListener('click', function () {
    // If the user agreed to get notified
    if (Notification &amp;&amp; Notification.permission === "granted") {
      var n = new Notification("Hi!");
    }
    // If the user hasn't told if he wants to be notified or not
    // Note: because of Chrome, we are not sure the permission property
    // is set, therefore it's unsafe to check for the "default" value.
    else if (Notification &amp;&amp; Notification.permission !== "denied") {
      Notification.requestPermission(function (status) {
        if (Notification.permission !== status) {
          Notification.permission = status;
        }
        // If the user said okay
        if (status === "granted") {
          var n = new Notification("Hi!");
        }
        // Otherwise, we can fallback to a regular modal alert
        else {
          alert("Hi!");
        }
      });
    }
    // If the user refuses to get notified
    else {
      // We can fallback to a regular modal alert
      alert("Hi!");
    }
  });
});</pre>

<h3 id="現場測試結果">現場測試結果</h3>

<p>若無法顯示，可至本文右上角「Language」切換回英文原文觀看。</p>

<p>{{ EmbedLiveSample('Simple_example', '100%', 30) }}</p>

<h2 id="處理多筆通知">處理多筆通知</h2>

<p>某些情況下 (如某個即時訊息 App 持續通知每一筆進來的訊息)，使用者可能會接收大量的通知。為了避免太多非必要訊息擠爆使用者的桌面，則應該讓等待中的通知進入佇列。</p>

<p>將標籤添加至任何新的通知，即可達到佇列效果。若通知擁有相同的標籤且尚未顯示，則新通知就會取代先前的通知；反之，若已顯示了相同標籤的通知，就會關閉先前的通知而顯示新通知。</p>

<h3 id="標籤範例">標籤範例</h3>

<p>先假設下列基本 HTML：</p>

<pre class="brush: html">&lt;button&gt;Notify me!&lt;/button&gt;</pre>

<p>則能以下列方式處理多筆通知：</p>

<pre class="brush: js">window.addEventListener('load', function () {
  // At first, let's check if we have permission for notification
  // If not, let's ask for it
  if (Notification &amp;&amp; Notification.permission !== "granted") {
    Notification.requestPermission(function (status) {
      if (Notification.permission !== status) {
        Notification.permission = status;
      }
    });
  }
  var button = document.getElementsByTagName('button')[0];
  button.addEventListener('click', function () {
    // If the user agreed to get notified
    // Let's try to send ten notifications
    if (Notification &amp;&amp; Notification.permission === "granted") {
      for (var i = 0; i &lt; 10; i++) {
        // Thanks to the tag, we should only see the "Hi! 10" notification
        var n = new Notification("Hi! " + i, {tag: 'soManyNotification'});
      }
    }
    // If the user hasn't told if he wants to be notified or not
    // Note: because of Chrome, we are not sure the permission property
    // is set, therefore it's unsafe to check for the "default" value.
    else if (Notification &amp;&amp; Notification.permission !== "denied") {
      Notification.requestPermission(function (status) {
        if (Notification.permission !== status) {
          Notification.permission = status;
        }
        // If the user said okay
        if (status === "granted") {
          for (var i = 0; i &lt; 10; i++) {
            // Thanks to the tag, we should only see the "Hi! 10" notification
            var n = new Notification("Hi! " + i, {tag: 'soManyNotification'});
          }
        }
        // Otherwise, we can fallback to a regular modal alert
        else {
          alert(Hi!");
        }
      });
    }
    // If the user refuses to get notified
    else {
      // We can fallback to a regular modal alert
      alert(Hi!");
    }
  });
});</pre>

<h3 id="現場測試結果_2">現場測試結果</h3>

<p>若無法顯示，可至本文右上角「Language」切換回英文原文觀看。</p>

<p>{{ EmbedLiveSample('Tag_example', '100%', 30) }}</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('Web Notifications')}}</td>
   <td>{{Spec2('Web Notifications')}}</td>
   <td>Initial specification.</td>
  </tr>
 </tbody>
</table>

<h2 id="瀏覽器相容性">瀏覽器相容性</h2>

<p>{{page("/en-US/Web/API/Notification","Browser compatibility")}}</p>

<h2 id="另可參閱">另可參閱</h2>

<ul>
 <li>{{ domxref("Notification") }}</li>
</ul>