notifications.bs

<pre class=metadata>
Group: WHATWG
H1: Notifications API
Shortname: notifications
Text Macro: TWITTER notifyapi
Abstract: This standard defines an API to display notifications to the end user, typically outside the top-level browsing context's viewport. It is designed to be compatible with existing notification systems, while remaining platform-independent.
Translation: ja https://triple-underscore.github.io/notifications-ja.html
Translation: zh-cn https://w3c-html-ig-zh.github.io/notifications/whatwg/
</pre>

<h2 id=terminology>Terminology</h2>

<p>This specification depends on the Infra Standard. [[!INFRA]]

<p>Some terms used in this specification are defined in the DOM, Fetch, HTML, IDL, Service Workers,
URL, and Vibration API Standards.
[[!DOM]]
[[!FETCH]]
[[!HTML]]
[[!WEBIDL]]
[[!SERVICE-WORKERS]]
[[!URL]]
[[!VIBRATION]]


<h2 id=notifications>Notifications</h2>

<p>A <dfn id=concept-notification>notification</dfn> is an abstract
representation of something that happened, such as the delivery of a message.

<p>A <a>notification</a> <em>can</em> have an associated
<dfn for=notification id=service-worker-registration>service worker registration</dfn>.

<p>A <a>notification</a> has an associated
<dfn for=notification id=concept-title>title</dfn> which is a DOMString.

<p>A <a>notification</a> has an associated
<dfn for=notification id=body>body</dfn> which is a DOMString.

<p>A <a>notification</a> has an associated
<dfn for=notification id=concept-direction>direction</dfn> which is one of
<i>auto</i>, <i>ltr</i>, and <i>rtl</i>.

<p>A <a>notification</a> has an associated
<dfn for=notification id=concept-language>language</dfn> which is a DOMString
representing either a valid BCP 47 language tag or the empty string.

<p>A <a>notification</a> has an associated
<dfn for=notification id=tag>tag</dfn> which is a DOMString.

<p>A <a>notification</a> has an associated
<dfn for=notification id=data>data</dfn>.

<p>A <a>notification</a> has an associated <dfn for=notification id=timestamp>timestamp</dfn> which
is a {{DOMTimeStamp}} representing the time, in milliseconds since 00:00:00 UTC on 1 January 1970,
of the event for which the notification was created.

<p class=note>Timestamps can be used to indicate the time at which a notification
is actual. For example, this could be in the past when a notification is used for
a message that couldn't immediately be delivered because the device was offline,
or in the future for a meeting that is about to start.

<p>A <a>notification</a> has an associated
<dfn for=notification id=concept-origin>origin</dfn>.

<p>A <a>notification</a> has an associated
<dfn for=notification id=renotify-preference-flag>renotify preference flag</dfn> which is initially
unset. When set indicates that the end user should be alerted after the <a>replace steps</a> have
run.

<p>A <a>notification</a> has an associated
<dfn for=notification id=silent-preference-flag>silent preference flag</dfn> which is initially
unset. When set indicates that no sounds or vibrations should be made.

<p>A <a>notification</a> has an associated
<dfn for=notification id=require-interaction-preference-flag>require interaction preference flag</dfn>
which is initially unset. When set, indicates that on devices with a sufficiently large screen, the
notification should remain readily available until the user activates or dismisses the notification.

<p>A <a>notification</a> <em>can</em> have these associated graphics: an
<dfn for=notification id=image-url>image URL</dfn>,
<dfn for=notification id=icon-url>icon URL</dfn>, and
<dfn for=notification id=badge-url>badge URL</dfn>; and their corresponding
<a for=notification>image resource</a>, <a for=notification>icon resource</a>, and
<a for=notification>badge resource</a>.

<p>An <dfn for=notification id=image-resource>image resource</dfn> is a picture shown as part of the
content of the <a>notification</a>, and should be displayed with higher visual priority than the
<a for=notification>icon resource</a> and <a for=notification>badge resource</a>, though it may be
displayed in fewer circumstances.

<p>An <dfn for=notification id=icon-resource>icon resource</dfn> is an image that reinforces the
<a>notification</a> (such as an icon, or a photo of the sender).

<p>A <dfn for=notification id=badge-resource>badge resource</dfn> is an icon representing the web
application, or the category of the <a>notification</a> if the web application sends a wide variety
of <a>notifications</a>. It <em>may</em> be used to represent the <a>notification</a> when there is
not enough space to display the <a>notification</a> itself. It <em>may</em> also be displayed inside
the <a>notification</a>, but then it should have less visual priority than the
<a for=notification>image resource</a> and <a for=notification>icon resource</a>.

<p>A <a>notification</a> <em>can</em> have a <dfn for=notification id=sound-url>sound URL</dfn>,
<dfn for=notification id=sound-resource>sound resource</dfn>,
<dfn for=notification id=vibration-pattern>vibration pattern</dfn>.

<p class=note>Developers are encouraged to not convey information through an
<a for=notification lt="image resource">image</a>, <a for=notification lt="icon resource">icon</a>,
<a for=notification lt="badge resource">badge</a>,
<a for=notification lt="sound resource">sound</a>, or <a for=notification>vibration pattern</a> that
is not otherwise accessible to the end user, especially since notification platforms that do not
support these features might ignore them.

<p>A <a>notification</a> has an associated list of
zero or more <dfn for=notification lt=action id=actions>actions</dfn>. Each
<a for=notification>action</a> has an associated
<dfn for=action id=action-title>title</dfn> and <dfn for=action id=action-name>name</dfn> and
<em>can</em> have an associated <dfn for=action>icon URL</dfn> and
<dfn for=action>icon resource</dfn>. Users may activate actions, as alternatives to
activating the notification itself. The user agent must determine the
<dfn>maximum number of actions</dfn> supported, within the constraints of the
notification platform.

<p class=note>Since display of actions is platform-dependent, developers are
encouraged to make sure that any action a user can invoke from a notification is
also available within the web application.

<p class="note no-backref">Some platforms might modify an <a for=action>icon resource</a> to better
match the platform's visual style before displaying it to the user, for example by rounding the
corners or painting it in a specific color. Developers are encouraged to use an icon that handles
such cases gracefully and does not lose important information through, e.g., loss of color or
clipped corners.

<p>A <dfn>non-persistent notification</dfn> is a
<a>notification</a> without an associated
<a for=notification>service worker registration</a>.

<p>A <dfn>persistent notification</dfn> is a
<a>notification</a> with an associated
<a for=notification>service worker registration</a>.

<p>A <var>notification</var> is considered to be
<dfn for=notification id=replaceable>replaceable</dfn> if there is a <a>notification</a> in the
<a>list of notifications</a> whose <a for=notification>tag</a> is not the empty string and equals
the <var>notification</var>'s <a>tag</a>, and whose <a for=notification>origin</a> is
<a>same origin</a> with <var>notification</var>'s <a for=notification>origin</a>.

<!-- XXX https://html.spec.whatwg.org/#fingerprinting-vector -->

<hr>

<p>To <dfn lt="create a notification|creating a notification">create a notification</dfn>, given a
<var>title</var>, <var>options</var>, and optionally a <var>serviceWorkerRegistration</var>, run
these steps:

<ol>
  <li><p>Let <var>notification</var> be a new
  <a>notification</a>.

  <li><p>If a <var>serviceWorkerRegistration</var> was provided, set
  <var>notification</var>'s <a for=notification>service worker registration</a> to
  <var>serviceWorkerRegistration</var>.

  <li><p>If a <var>serviceWorkerRegistration</var> was not provided and
  <var>options</var>'s <code>actions</code> is not empty, <a>throw</a> a
  <code>TypeError</code> exception.

  <p class=note><a>Actions</a> are only currently supported for
  <a>persistent notifications</a>.

  <li><p>If <var>options</var>'s <code>silent</code> is true, and either
  <var>options</var>'s <code>sound</code> is present or <var>options</var>'s
  <code>vibrate</code> is present, <a>throw</a> a <code>TypeError</code>
  exception.

  <li><p>If <var>options</var>'s <code>renotify</code> is true and
  <var>options</var>'s <code>tag</code> is the empty string, <a>throw</a> a
  <code>TypeError</code> exception.

  <li><p>Set <var>notification</var>'s <a for=notification>data</a> to
  <a abstract-op>StructuredSerializeForStorage</a>(<var>options</var>'s <code>data</code>). Rethrow
  any exceptions.

  <li><p>Set <var>notification</var>'s <a for=notification>title</a> to <var>title</var>.

  <li><p>Set <var>notification</var>'s
  <a for=notification>direction</a> to <var>options</var>'s
  <code>dir</code>.

  <li><p>Set <var>notification</var>'s <a for=notification>language</a> to
  <var>options</var>'s <code>lang</code>.

  <li><p>Set <var>notification</var>'s <a for=notification>origin</a> to the
  <a>entry settings object</a>'s <a for="environment settings object">origin</a>.

  <li><p>Set <var>notification</var>'s <a for=notification>body</a> to <var>options</var>'s
  <code>body</code>.

  <li><p>Set <var>notification</var>'s <a for=notification>tag</a> to <var>options</var>'s
  <code>tag</code>.

  <li><p>Let <var>baseURL</var> be the API base URL specified by the
  <a>entry settings object</a>. <span class=XXX>Or incumbent?</span>

  <li><p>If <var>options</var>'s <code>image</code> is present,
  <a lt="url parser">parse</a> it using <var>baseURL</var>, and if that does not
  return failure, set <var>notification</var>'s <a>image URL</a> to the return
  value. (Otherwise <a>image URL</a> is not set.)

  <li><p>If <var>options</var>'s <code>icon</code> is present,
  <a lt="url parser">parse</a> it using <var>baseURL</var>, and if that does not
  return failure, set <var>notification</var>'s <a for=notification>icon URL</a> to the return
  value. (Otherwise <a for=notification>icon URL</a> is not set.)

  <li><p>If <var>options</var>'s <code>badge</code> is present,
  <a lt="url parser">parse</a> it using <var>baseURL</var>, and if that does not
  return failure, set <var>notification</var>'s <a for=notification>badge URL</a> to the return
  value. (Otherwise <a for=notification>badge URL</a> is not set.)

  <li><p>If <var>options</var>'s <code>sound</code> is present,
  <a lt="url parser">parse</a> it using <var>baseURL</var>, and if that does not
  return failure, set <var>notification</var>'s <a for=notification>sound URL</a> to the return
  value. (Otherwise <a for=notification>sound URL</a> is not set.)

  <li><p>If <var>options</var>'s <code>vibrate</code> is present,
  <a>validate and normalize</a> it and set <var>notification</var>'s
  <a for=notification>vibration pattern</a> to the return value. (Otherwise
  <a for=notification>vibration pattern</a> is not set.)

  <li><p>If <var>options</var>'s <code>timestamp</code> is present, set
  <var>notification</var>'s <a for=notification>timestamp</a> to the value. Otherwise, set
  <var>notification</var>'s <a for=notification>timestamp</a> to the number of milliseconds that
  passed between 00:00:00 UTC on 1 January 1970 and the time at which the
  <code>Notification</code> constructor was called.

  <li><p>If <var>options</var>'s <code>renotify</code> is true, set
  <var>notification</var>'s <a for=notification>renotify preference flag</a>.

  <li><p>If <var>options</var>'s <code>silent</code> is true, set
  <var>notification</var>'s <a for=notification>silent preference flag</a>.

  <li><p>If <var>options</var>'s <code>requireInteraction</code> is true, set
  <var>notification</var>'s <a for=notification>require interaction preference flag</a>.

  <li><p>Set <var>notification</var>'s list of <a>actions</a> to an empty list,
  then for each <var>entry</var> in <var>options</var>'s <code>actions</code>,
  up to the <a>maximum number of actions</a> supported (skip any excess
  entries), perform the following steps:

  <ol>
    <li><p>Let <var>action</var> be a new <a lt="actions">action</a>.

    <li><p>Set <var>action</var>'s <a for=action>name</a> to the <var>entry</var>'s
    <code>action</code>.

    <li><p>Set <var>action</var>'s <a for=action>title</a> to the
    <var>entry</var>'s <code>title</code>.

    <li><p>If <var>entry</var>'s <code>icon</code> is present,
    <a lt="url parser">parse</a> it using <var>baseURL</var>, and if that does
    not return failure, set <var>action</var>'s <a for=action>icon URL</a> to the
    return value. (Otherwise <a for=action>icon URL</a> is not set.)

    <li><p>Append <var>action</var> to <var>notification</var>'s list of
    <a>actions</a>.
  </ol>

  <li><p>Return <var>notification</var>.
</ol>


<h3 id=lifetime-and-ui-integrations>Lifetime and UI integration</h3>

<p>The user agent must keep a <dfn>list of notifications</dfn>, which is a <a for=/>list</a> of zero
or more <a>notifications</a>.

<p>User agents should run the <a>close steps</a> for a
<a>non-persistent notification</a> a couple of seconds after they have been
created.

<p>User agents should not display <a>non-persistent notification</a> in a
platform's "notification center" (if available).

<p>User agents should persist <a>persistent notifications</a> until they are
removed from the <a>list of notifications</a>.

<p class=example id=example-38bbd8ee>A <a>persistent notification</a> could have the
{{Notification/close()}} method invoked of one of its {{Notification}} objects.

<p>User agents should display <a>persistent notifications</a> in a platform's
"notification center" (if available).


<h3 id=permission-model>Permission model</h3>

<p><a>Notifications</a> can only be displayed if the
user (or user agent on behalf of the user) has granted <dfn>permission</dfn>.
The <a>permission</a> to show <a>notifications</a>
for a given <a for=/>origin</a> is one of three strings:

<dl>
  <dt>"<code>default</code>"
  <dd><p>This is equivalent to "<code>denied</code>", but the user has made no
  explicit choice thus far.

  <dt>"<code>denied</code>"
  <dd><p>This means the user does not want
  <a>notifications</a>.

  <dt>"<code>granted</code>"
  <dd><p>This means <a>notifications</a> can be
  displayed.
</dl>

<p class=note>There is no equivalent to "<code>default</code>"
meaning "<code>granted</code>". In that case
"<code>granted</code>" is simply returned as there would be no reason
for the application to ask for <a>permission</a>.


<h3 id=direction>Direction</h3>

<p>This section is written in terms equivalent to those used in the Rendering
section of HTML. [[!HTML]]

<!-- keep this in sync with
     https://html.spec.whatwg.org/multipage/rendering.html#text-rendered-in-native-user-interfaces -->

<p>User agents are expected to honor the Unicode semantics of the text of a
<a>notification</a>'s <a for=notification>title</a>, <a for=notification>body</a>, and the
<a for=action>title</a> of each of its <a for=notification>actions</a>. Each is expected
to be treated as an independent set of one or more bidirectional algorithm
paragraphs when displayed, as defined by the bidirectional algorithm's rules P1,
P2, and P3, including, for instance, supporting the paragraph-breaking behavior
of U+000A LINE FEED (LF) characters. For each paragraph of the
<a for=notification>title</a>, <a for=notification>body</a> and the
<a for=action>title</a> of each of the <a for=notification>actions</a>, the
<a>notification</a>'s
<a for=notification>direction</a> provides the higher-level override of
rules P2 and P3 if it has a value other than "<code>auto</code>". [[!BIDI]]

<p>The <a>notification</a>'s <a for=notification>direction</a> also determines the relative order in
which the <a>notification</a>'s <a for=notification>actions</a> should be displayed to the user, if
the notification platform displays them side by side.


<h3 id=language>Language</h3>

<!-- keep this in sync with
     https://html.spec.whatwg.org/multipage/dom.html#attr-lang -->

<p>The <a>notification</a>'s <a for=notification>language</a> specifies the primary language for the
<a>notification</a>'s <a for=notification>title</a>, <a for=notification>body</a> and the
<a for=notification>title</a> of each of its <a for=notification>actions</a>. Its value is a string.
The empty string indicates that the primary language is unknown. Any other string must be
interpreted as a language tag. Validity or well-formedness are not enforced. [[!LANG]]

<p class=note>Developers are encouraged to only use valid language tags.


<h3 id=resources>Resources</h3>

<p>The <dfn>fetch steps</dfn> for a given
<a>notification</a> <var>notification</var> are:

<ol>
 <!-- XXX https://www.w3.org/Bugs/Public/show_bug.cgi?id=24055 -->
 <li>
  <p>If the notification platform supports images, <a for=/>fetch</a>
  <var>notification</var>'s <a>image URL</a>, if <a>image URL</a> is set.

  <p class=note>The intent is to fetch this resource similar to an
  <a href="https://html.spec.whatwg.org/multipage/images.html#update-the-image-data"><code>&lt;img&gt;</code></a>,
  but this <a href="https://www.w3.org/Bugs/Public/show_bug.cgi?id=24055">needs abstracting</a>.

  <p>Then, <a>in parallel</a>:

  <ol>
   <li><p>Wait for the <a for=/>response</a>.

   <li><p>If the <a for=/>response</a>'s <a>internal response</a>'s <a for=response>type</a> is
   "<code>default</code>", then attempt to decode the resource as image.

   <li><p>If the image format is supported, set <var>notification</var>'s
   <a>image resource</a> to the decoded resource. (Otherwise
   <var>notification</var> has no <a>image resource</a>.)
  </ol>

 <li>
  <p>If the notification platform supports icons, <a for=/>fetch</a>
  <var>notification</var>'s <a for=notification>icon URL</a>, if <a for=notification>icon URL</a>
  is set.

  <p class=note>The intent is to fetch this resource similar to an
  <a href="https://html.spec.whatwg.org/multipage/images.html#update-the-image-data"><code>&lt;img&gt;</code></a>,
  but this <a href="https://www.w3.org/Bugs/Public/show_bug.cgi?id=24055">needs abstracting</a>.

  <p>Then, <a>in parallel</a>:

  <ol>
   <li><p>Wait for the <a for=/>response</a>.

   <li><p>If the <a for=/>response</a>'s <a>internal response</a>'s <a for=response>type</a> is
   "<code>default</code>", then attempt to decode the resource as image.

   <li><p>If the image format is supported, set <var>notification</var>'s
   <a for=notification>icon resource</a> to the decoded resource. (Otherwise
   <var>notification</var> has no <a for=notification>icon resource</a>.)
  </ol>
 </li>

 <li>
  <p>If the notification platform supports badges, <a for=/>fetch</a> <var>notification</var>'s
  <a for=notification>badge URL</a>, if <a for=notification>badge URL</a> is set.

  <p class=note>The intent is to fetch this resource similar to an
  <a href="https://html.spec.whatwg.org/multipage/images.html#update-the-image-data"><code>&lt;img&gt;</code></a>,
  but this <a href="https://www.w3.org/Bugs/Public/show_bug.cgi?id=24055">needs abstracting</a>.

  <p>Then, <a>in parallel</a>:

  <ol>
   <li><p>Wait for the <a for=/>response</a>.

   <li><p>If the <a for=/>response</a>'s <a>internal response</a>'s <a for=response>type</a> is
   "<code>default</code>", then attempt to decode the resource as image.

   <li><p>If the image format is supported, set <var>notification</var>'s
   <a for=notification>badge resource</a> to the decoded resource. (Otherwise
   <var>notification</var> has no <a for=notification>badge resource</a>.)
  </ol>
 </li>

 <li>
  <p>If the notification platform supports actions and action icons, then for each <var>action</var>
  in <var>notification</var>'s list of <a>actions</a> <a for=/>fetch</a> <var>action</var>'s
  <a for=action>icon URL</a>, if <a for=action>icon URL</a> is set.

  <p class=note>The intent is to fetch this resource similar to an
  <a href="https://html.spec.whatwg.org/multipage/images.html#update-the-image-data"><code>&lt;img&gt;</code></a>,
  but this <a href="https://www.w3.org/Bugs/Public/show_bug.cgi?id=24055">needs abstracting</a>.

  <p>Then, <a>in parallel</a>:

  <ol>
   <li><p>Wait for the <a for=/>response</a>.

   <li><p>If the <a for=/>response</a>'s <a>internal response</a>'s <a for=response>type</a> is
   "<code>default</code>", then attempt to decode the resource as image.

   <li><p>If the image format is supported, set <var>action</var>'s
   <a for=action>icon resource</a> to the decoded resource. (Otherwise
   <var>action</var> has no <a for=action>icon resource</a>.)
  </ol>
 </li>

 <li>
  <p>If the notification platform supports sounds, and the <var>notification</var>
  is either not <a>replaceable</a> or has the <a for=notification>renotify preference flag</a>
  set, <a for=/>fetch</a> <var>notification</var>'s <a for=notification>sound URL</a> if it has
  been set.

  <p>Then, <a>in parallel</a>:

  <ol>
   <li><p>Wait for the <a for=/>response</a>.

   <li><p>If the <a for=/>response</a>'s <a>internal response</a>'s <a for=response>type</a> is
   "<code>default</code>", then attempt to decode the resource as sound.
   <!-- XXX xref -->

   <li><p>If the sound format is supported, set <var>notification</var>'s
   <a>sound resource</a> to the decoded resource. (Otherwise
   <var>notification</var> has no <a>sound resource</a>.)
  </ol>
 </li>
</ol>


<h3 id=showing-a-notification>Showing a notification</h3>

<p>The <dfn>show steps</dfn> for a given
<a>notification</a> <var>notification</var> are:

<ol>
 <li><p>If <var>notification</var> is <a>replaceable</a>, then run the <a>replace steps</a> for that
 <a>notification</a> and <var>notification</var>.

 <li><p>Otherwise, run the <a>display steps</a> for <var>notification</var>.

 <li><p>If <var>notification</var> is a <a>non-persistent notification</a>, then
 <a>fire an event</a> named <code>show</code> on the {{Notification}} object representing
 <var>notification</var>.
</ol>


<h3 id=activating-a-notification>Activating a notification</h3>

<p>When a <a>notification</a> <var>notification</var>,
or one of its <a>actions</a>, is activated by the user, assuming the underlying
notification platform supports activation, the user agent must (unless otherwise
specified) run these steps:

<ol>
 <li>
  <p>If <var>notification</var> is a <a>persistent notification</a>, then:

  <ol>
   <li><p>Let <var>action</var> be the empty string.

   <li><p>If one of <var>notification</var>'s <a for=notification>actions</a> was activated by the
   user, then set <var>action</var> to that <a for=notification>action</a>'s <a for=action>name</a>.

   <li><p>Let <var>callback</var> be an algorithm that when invoked with a <var>global</var>,
   <a lt="fire a service worker notification event named e">fires a service worker notification event</a>
   named <code>notificationclick</code> given <var>notification</var> and <var>action</var> on
   <var>global</var>.

   <li><p>Then run <a>Handle Functional Event</a> with <var>notification</var>'s
   <a for=notification>service worker registration</a> and <var>callback</var>.
  </ol>

 <li>
  <p>Otherwise, <a>queue a task</a> to run these steps:

  <ol>
   <li>
    <p>Let <var>intoFocus</var> be the result of <a lt="fire an event">firing an event</a> named
    <code>click</code> on the {{Notification}} object representing <var>notification</var>, with its
    {{Event/cancelable}} attribute initialized to true.

    <p class="note">User agents are encouraged to make {{Window/focus()}} work from within the event
    listener for the event named <code>click</code>.

   <li><p>If <var>intoFocus</var> is true, then the user agent should bring the
   <var>notification</var>'s related <a for=/>browsing context</a>'s viewport into focus.
  </ol>
</ol>

<p class="note">Throughout the web platform "activate" is intentionally misnamed as "click".


<h3 id=closing-a-notification>Closing a notification</h3>

<p>When a <a>notification</a> is closed, either by the
underlying notification platform or by the user, the <a>close steps</a> for it
must be run.

<p>The <dfn>close steps</dfn> for a given <var>notification</var> are:

<ol>
 <li><p>If the <a>list of notifications</a> does not <a for=list>contain</a>
 <var>notification</var>, then abort these steps.

 <li><p><a>Handle close events</a> with <var>notification</var>.

 <li><p><a for=list>Remove</a> <var>notification</var> from the <a>list of notifications</a>.
</ol>

<p>To <dfn>handle close events</dfn> given a <var>notification</var>, run these steps:

<ol>
 <li>
  <p>If <var>notification</var> is a <a>persistent notification</a> and
  <var>notification</var> was closed by the user, then:

  <ol>
   <li><p>Let <var>callback</var> be an algorithm that when invoked with a <var>global</var>,
   <a lt="fire a service worker notification event named e">fires a service worker notification event</a>
   named <code>notificationclose</code> given <var>notification</var> on <var>global</var>.

   <li><p>Then run <a>Handle Functional Event</a> with <var>notification</var>'s
   <a for=notification>service worker registration</a> and <var>callback</var>.
  </ol>

 <li><p>If <var>notification</var> is a <a>non-persistent notification</a>, then
 <a>fire an event</a> named <code>close</code> on the {{Notification}} object representing
 <var>notification</var>.
</ol>


<h3 id=displaying-notification>Displaying notifications</h3>

<p>The <dfn>display steps</dfn> for a given <var>notification</var> are:

<ol>
  <li><p>Wait for any <a for=/ lt=fetch>fetches</a> to complete and <var>notification</var>'s
  <a for=notification>image resource</a> <a for=notification>icon resource</a>,
  <a for=notification>badge resource</a>, and <a for=notification>sound resource</a> to be set
  (if any), as well as the <a for=action>icon resources</a> for the <var>notification</var>'s
  <a for=notification>actions</a> (if any).

  <li><p>Display <var>notification</var> on the device (e.g., by calling the
  appropriate notification platform API).

  <li><p>Run the <a>alert steps</a> for <var>notification</var>.

  <li><p><a for=list>Append</a> <var>notification</var> to the <a>list of notifications</a>.
</ol>


<h3 id=replacing-a-notification>Replacing a notification</h3>

<p>The <dfn>replace steps</dfn> for replacing an <var>old</var>
<a>notification</a> with a <var>new</var> one are:

<ol>
  <li><p>Wait for any <a for=/ lt=fetch>fetches</a> to complete and <var>notification</var>'s
  <a for=notification>image resource</a> <a for=notification>icon resource</a>,
  <a for=notification>badge resource</a>, and <a for=notification>sound resource</a> to be set
  (if any), as well as the <a for=action>icon resources</a> for the <var>notification</var>'s
  <a for=notification>actions</a> (if any).

  <li><p><a for=list>Replace</a> <var>old</var> with <var>new</var>, in the same position, in the
  <a>list of notifications</a>.

  <li><p><a>Handle close events</a> with <var>old</var>.

  <li><p>If <var>notification</var>'s <a for=notification>renotify preference flag</a> has been set,
  perform the <a>alert steps</a> for <var>new</var>.
</ol>

<p>If the notification platform does not support replacement this requirement may be
addressed by running the <a>close steps</a> for <var>old</var> and then running the
<a>display steps</a> for <var>new</var>.

<p class="note no-backref">Notification platforms are strongly encouraged to support
native replacement. It is much nicer and has no side effects, such as playing sounds
or vibrating the device again, unless the <a for=notification>renotify preference flag</a> is set.


<h3 id=alerting-the-user>Alerting the user</h3>

<p>The <dfn>alert steps</dfn> for alerting the user about a given
<var>notification</var> are:

<ol>
 <li><p>Play the <var>notification</var>'s <a>sound resource</a>, if any.

 <li><p><a>Perform vibration</a> using <var>notification</var>'s
 <a for=notification>vibration pattern</a>, if any.
</ol>


<h2 id=api>API</h2>

<pre class=idl>
[Constructor(DOMString title, optional NotificationOptions options),
 Exposed=(Window,Worker)]
interface Notification : EventTarget {
  static readonly attribute NotificationPermission permission;
  [Exposed=Window] static Promise&lt;NotificationPermission> requestPermission(optional NotificationPermissionCallback deprecatedCallback);

  static readonly attribute unsigned long maxActions;

  attribute EventHandler onclick;
  attribute EventHandler onshow;
  attribute EventHandler onerror;
  attribute EventHandler onclose;

  readonly attribute DOMString title;
  readonly attribute NotificationDirection dir;
  readonly attribute DOMString lang;
  readonly attribute DOMString body;
  readonly attribute DOMString tag;
  readonly attribute USVString image;
  readonly attribute USVString icon;
  readonly attribute USVString badge;
  readonly attribute USVString sound;
  [SameObject] readonly attribute FrozenArray&lt;unsigned long> vibrate;
  readonly attribute DOMTimeStamp timestamp;
  readonly attribute boolean renotify;
  readonly attribute boolean silent;
  readonly attribute boolean requireInteraction;
  [SameObject] readonly attribute any data;
  [SameObject] readonly attribute FrozenArray&lt;NotificationAction> actions;

  void close();
};

dictionary NotificationOptions {
  NotificationDirection dir = "auto";
  DOMString lang = "";
  DOMString body = "";
  DOMString tag = "";
  USVString image;
  USVString icon;
  USVString badge;
  USVString sound;
  VibratePattern vibrate;
  DOMTimeStamp timestamp;
  boolean renotify = false;
  boolean silent = false;
  boolean requireInteraction = false;
  any data = null;
  sequence&lt;NotificationAction> actions = [];
};

enum NotificationPermission {
  "default",
  "denied",
  "granted"
};

enum NotificationDirection {
  "auto",
  "ltr",
  "rtl"
};

dictionary NotificationAction {
  required DOMString action;
  required DOMString title;
  USVString icon;
};

callback NotificationPermissionCallback = void (NotificationPermission permission);
</pre>

<p>A <a>non-persistent notification</a> is represented by one {{Notification}}
object and can be created through {{Notification}}'s
<a constructor lt="Notification(title, options)">constructor</a>.

<p>A <a>persistent notification</a> is represented by zero or more
{{Notification}} objects and can be created through the
{{ServiceWorkerRegistration/showNotification()}} method.


<h3 id=garbage-collection>Garbage collection</h3>

<p>A {{Notification}} object must not be garbage collected while the <a>list of notifications</a>
<a for=list>contains</a> its corresponding <a>notification</a> and it has an
<a for=/>event listener</a> whose <b>type</b> is <code>click</code>, <code>show</code>,
<code>close</code>, or <code>error</code>.


<h3 id=constructors>Constructors</h3>

<p>The <dfn constructor for=Notification><code>Notification(title, options)</code></dfn>
constructor, when invoked, must run these steps:

<ol>
  <li><p>If the <a>current global object</a> is a {{ServiceWorkerGlobalScope}} object, then
  <a>throw</a> a <code>TypeError</code> exception.

  <li><p>Let <var>notification</var> be the result of <a>creating a notification</a> given
  <var>title</var> and <var>options</var>. Rethrow any exceptions.

  <li><p>Let <var>n</var> be a new {{Notification}} object associated with
  <var>notification</var>.

  <li><p>Run these steps <a>in parallel</a>:

  <ol>
    <li><p>If <a>permission</a> for <var>notification</var>'s <a for=notification>origin</a> is not
    "<code>granted</code>", then <a>queue a task</a> to <a>fire an event</a> named
    <code>error</code> on <var>n</var>, and abort these steps.

    <li><p>Run the <a>fetch steps</a> for <var>notification</var>.

    <li><p>Run the <a>show steps</a> for <var>notification</var>.
  </ol>

  <li><p>Return <var>n</var>.
</ol>


<h3 id=static-members>Static members</h3>

<p>The static <dfn attribute for=Notification><code>permission</code></dfn>
attribute's getter must return <a>permission</a> for the
<a>entry settings object</a>'s <a for="environment settings object">origin</a>.

<p class=note>If you edit standards please refrain from copying the above. Synchronous
permissions are like synchronous IO, a bad idea.

<p>The static
<dfn method for=Notification><code>requestPermission(<var>deprecatedCallback</var>)</code></dfn>
method, when invoked, must run these steps:

<ol>
 <li><p>Let <var>promise</var> be a new promise.

 <li>
  <p>Run these steps <a>in parallel</a>:

  <ol>
   <li><p>Let <var>permission</var> be <a>permission</a> for
   <a>entry settings object</a>'s <a for="environment settings object">origin</a>.
   <!-- XXX context object's global object's environment settings object's origin -->

   <li><p>If <var>permission</var> is "<code>default</code>", ask the user whether showing
   notifications for the <a>entry settings object</a>'s
   <a for="environment settings object">origin</a> is acceptable. If it is, set
   <var>permission</var> to "<code>granted</code>", and "<code>denied</code>" otherwise.

   <li>
    <p><a>Queue a task</a> to run these steps:

    <ol>
     <li><p>Set <a>permission</a> for the <a>entry settings object</a>'s
     <a for="environment settings object">origin</a> to <var>permission</var>.

     <li><p>If <var>deprecatedCallback</var> is given, invoke
     <var>deprecatedCallback</var> with <var>permission</var> as single argument. If this
     throws an exception, <a>report the exception</a>.

     <li><p>Fullfil <var>promise</var> with <var>permission</var>.
    </ol>
  </ol>

 <li><p>Return <var>promise</var>.
</ol>

<p class="warning">Notifications are the one instance thus far where asking the
user upfront makes sense. Specifications for other APIs should not use this
pattern and instead employ one of the
<a href="http://robert.ocallahan.org/2011/06/permissions-for-web-applications_30.html">
many more suitable alternatives</a>.

<p>The static <dfn attribute for=Notification><code>maxActions</code></dfn>
attribute's getter must return the <a>maximum number of actions</a> supported.

<h3 id=object-members>Object members</h3>

<p>The following are the <a>event handlers</a> (and their corresponding
<a>event handler event types</a>) that must be supported as attributes by the
{{Notification}} object.

<table>
  <thead>
    <tr>
      <th><a>event handler</a>
      <th><a>event handler event type</a>
 <tbody>
  <tr>
   <td><dfn attribute for=Notification><code>onclick</code></dfn>
   <td><code>click</code>
  <tr>
   <td><dfn attribute for=Notification><code>onshow</code></dfn>
   <td><code>show</code>
  <tr>
   <td><dfn attribute for=Notification><code>onerror</code></dfn>
   <td><code>error</code>
  <tr>
   <td><dfn attribute for=Notification><code>onclose</code></dfn>
   <td><code>close</code>
</table>

<p>The <dfn method for=Notification><code>close()</code></dfn> method, when
invoked, must run the <a>close steps</a> for the
<a>notification</a>.

<p>The <dfn attribute for=Notification><code>title</code></dfn> attribute's getter must return the
<a>notification</a>'s <a for=notification>title</a>.

<p>The <dfn attribute for=Notification><code>dir</code></dfn> attribute's getter must return the
<a>notification</a>'s <a for=notification>direction</a>.

<p>The <dfn attribute for=Notification><code>lang</code></dfn> attribute's getter must return the
<a>notification</a>'s <a for=notification>language</a>.

<p>The <dfn attribute for=Notification><code>body</code></dfn> attribute's getter must return the
<a>notification</a>'s <a for=notification>body</a>.

<p>The <dfn attribute for=Notification><code>tag</code></dfn> attribute's getter must return the
<a>notification</a>'s <a for=notification>tag</a>.

<p>The <dfn attribute dfn-for=Notification><code>image</code></dfn> attribute's getter must return
the <a>notification</a>'s <a for=notification>image URL</a>, <a lt="url serializer">serialized</a>,
and the empty string if there is no <a>notification</a>'s <a for=notification>image URL</a>
otherwise.

<p>The <dfn attribute for=Notification><code>icon</code></dfn> attribute's getter must return the
<a>notification</a>'s <a for=notification>icon URL</a>, <a lt="url serializer">serialized</a>, and
the empty string if there is no <a>notification</a>'s <a for=notification>icon URL</a> otherwise.

<p>The <dfn attribute for=Notification><code>badge</code></dfn> attribute's getter must return the
<a>notification</a>'s <a for=notification>badge URL</a>, <a lt="url serializer">serialized</a>, and
the empty string if there is no <a>notification</a>'s <a for=notification>badge URL</a> otherwise.

<p>The <dfn attribute for=Notification><code>sound</code></dfn> attribute's getter must return the
<a>notification</a>'s <a for=notification>sound URL</a>, <a lt="url serializer">serialized</a>, and
the empty string if there is no <a>notification</a>'s <a for=notification>sound URL</a> otherwise.

<p>The <dfn attribute for=Notification><code>vibrate</code></dfn> attribute's getter must return the
<a>notification</a>'s <a for=notification>vibration pattern</a>, if any, and the empty list
otherwise.

<p>The <dfn attribute for=Notification><code>timestamp</code></dfn> attribute's getter must return
the <a>notification</a>'s <a for=notification>timestamp</a>.

<p>The <dfn attribute for=Notification><code>renotify</code></dfn> attribute's getter must return
the <a>notification</a>'s <a for=notification>renotify preference flag</a>.

<p>The <dfn attribute for=Notification><code>silent</code></dfn> attribute's getter must return the
<a>notification</a>'s <a for=notification>silent preference flag</a>.

<p>The <dfn attribute for=Notification><code>requireInteraction</code></dfn> attribute's getter must
return the <a>notification</a>'s <a for=notification>require interaction preference flag</a>.

<p>The <dfn attribute for=Notification><code>data</code></dfn> attribute's getter must return
<a abstract-op>StructuredDeserialize</a>(<a>notification</a>'s <a for=notification>data</a>,
<a>context object</a>'s <a>relevant Realm</a>). If this throws an exception, then return null.
<!-- Relies on SameObject becoming Cached as proposed -->

<p>The <dfn attribute for=Notification><code>actions</code></dfn> attribute's getter must return the
result of the following steps:

<ol>
  <li><p>Let <var>frozenActions</var> be an empty list of type {{NotificationAction}}.

  <li><p>For each <var>entry</var> in the <a>notification</a>'s list of
  <a for=notification>actions</a>, perform the following steps:

  <ol>
    <li><p>Let <var>action</var> be a new {{NotificationAction}}.

    <li><p>Set <var>action</var>'s {{NotificationAction/action}} to
    <var>entry</var>'s <a for=action>name</a>.

    <li><p>Set <var>action</var>'s {{NotificationAction/title}} to
    <var>entry</var>'s <a for=action>title</a>.

    <li><p>Set <var>action</var>'s {{NotificationAction/icon}} to
    <var>entry</var>'s <a for=action>icon URL</a>.

    <!-- XXX IDL dictionaries are usually returned by value, so don't need to be
         immutable. But FrozenArray reifies the dictionaries to mutable JS
         objects accessed by reference, so we explicitly freeze them.
         It would be better to do this with IDL primitives instead of JS - see
         https://www.w3.org/Bugs/Public/show_bug.cgi?id=29004 -->
    <li><p>Call <a lt="freeze">Object.freeze</a> on <var>action</var>, to
    prevent accidental mutation by scripts.

    <li><p>Append <var>action</var> to <var>frozenActions</var>.
  </ol>

  <li><p><a>Create a frozen array</a> from <var>frozenActions</var>.
</ol>

<h3 id=examples>Examples</h3>

<h4 id=using-events>Using events from a page</h4>

<p><a lt="non-persistent notification">Non-persistent</a> {{Notification}}
objects dispatch events during their lifecycle, which developers can use to
generate desired behaviors.

<p>The <code>click</code> event dispatches when the user activates a
notification.

<pre class=example id=example-08e8ecea>
var not = new Notification("Gebrünn Gebrünn by Paul Kalkbrenner", { icon: "newsong.svg", tag: "song" });
not.onclick = function() { displaySong(this); };</pre>


<h4 id=using-actions>Using actions from a service worker</h4>

<p><a lt="persistent notification">Persistent notifications</a> fire
<code>notificationclick</code> events on the {{ServiceWorkerGlobalScope}}.

<p>Here a service worker shows a notification with a single "Archive"
<a lt="actions">action</a>, allowing users to perform this common task from the
notification without having to open the website (for example the notification
platform might show a button on the notification). The user can also activate
the main body of the notification to open their inbox.

<pre class=example id=example-50e7c86c>
self.registration.showNotification("New mail from Alice", {
  actions: [{action: 'archive', title: "Archive"}]
});

self.addEventListener('notificationclick', function(event) {
  event.notification.close();
  if (event.action === 'archive') {
    silentlyArchiveEmail();
  } else {
    clients.openWindow("/inbox");
  }
}, false);</pre>


<h4 id=tags-example>Using the <code>tag</code> member for multiple instances</h4>

<p>Web applications frequently operate concurrently in multiple instances, such
as when a user opens a mail application in multiple browser tabs. Since the
desktop is a shared resource, the notifications API provides a way for these
instances to easily coordinate, by using the <code>tag</code> member.

<p>Notifications which represent the same conceptual event can be tagged in the
same way, and when both are shown, the user will only receive one notification.

<pre class=example id=example-2e2c735a>
Instance 1                                   | Instance 2
                                             |
// Instance notices there is new mail.       |
new Notification("New mail from John Doe",   |
                 { tag: 'message1' });       |
                                             |
                                             |  // Slightly later, this instance notices
                                             |  // there is new mail.
                                             |  new Notification("New mail from John Doe",
                                             |                   { tag: 'message1' });</pre>

<p>The result of this situation, if the user agent follows the algorithms here, is a
<strong>single</strong> notification "New mail from John Doe".


<h4 id=using-the-tag-member-for-a-single-instance>Using the <code>tag</code> member for a single instance</h4>

<p>The <code>tag</code> member can also be used by a single instance of an
application to keep its notifications as current as possible as state changes.

<p>For example, if Alice is using a chat application with Bob, and Bob sends
multiple messages while Alice is idle, the application may prefer that Alice not
see a desktop notification for each message.

<pre class=example id=example-a1d95db4>
// Bob says "Hi"
new Notification("Bob: Hi", { tag: 'chat_Bob' });

// Bob says "Are you free this afternoon?"
new Notification("Bob: Hi / Are you free this afternoon?", { tag: 'chat_Bob' });</pre>

<p>The result of this situation is a <i>single</i> notification; the second one
replaces the first having the same tag. In a platform that queues notifications
(first-in-first-out), using the tag allows the notification to also maintain its
position in the queue. Platforms where the newest notifications are shown first,
a similar result could be achieved using the {{Notification/close()}} method.


<h2 id=service-worker-api>Service worker API</h2>

<pre class=idl>
dictionary GetNotificationOptions {
  DOMString tag = "";
};

partial interface ServiceWorkerRegistration {
  Promise&lt;void> showNotification(DOMString title, optional NotificationOptions options);
  Promise&lt;sequence&lt;Notification>> getNotifications(optional GetNotificationOptions filter);
};

[Constructor(DOMString type, NotificationEventInit eventInitDict),
 Exposed=ServiceWorker]
interface NotificationEvent : ExtendableEvent {
  readonly attribute Notification notification;
  readonly attribute DOMString action;
};

dictionary NotificationEventInit : ExtendableEventInit {
  required Notification notification;
  DOMString action = "";
};

partial interface ServiceWorkerGlobalScope {
  attribute EventHandler onnotificationclick;
  attribute EventHandler onnotificationclose;
};
</pre>

<p>The
<dfn method for=ServiceWorkerRegistration><code>showNotification(title, options)</code></dfn>
method, when invoked, must run these steps:

<ol>
  <li><p>Let <var>promise</var> be a new promise.

  <li><p>If the <a>context object</a>'s <a for="service worker registration">active worker</a> is
  null, then reject <var>promise</var> with a <code>TypeError</code> exception and return
  <var>promise</var>.

  <li><p>Let <var>serviceWorkerRegistration</var> be the <a>context object</a>.

  <li><p>Let <var>notification</var> be the result of <a>creating a notification</a> given
  <var>title</var>, <var>options</var>, and <var>serviceWorkerRegistration</var>. If this threw an
  exception, reject <var>promise</var> with that exception and return <var>promise</var>.

  <li><p>Run these steps <a>in parallel</a>:

  <ol>
    <li><p>If <a>permission</a> for <var>notification</var>'s <a for=notification>origin</a> is not
    "<code>granted</code>", then reject <var>promise</var> with a <code>TypeError</code> exception,
    and abort these steps.

    <li><p>Run the <a>fetch steps</a> for <var>notification</var>.

    <li><p>Run the <a>show steps</a> for <var>notification</var>.

    <li><p>Resolve <var>promise</var> with undefined.
  </ol>

  <li><p>Return <var>promise</var>.
</ol>

<p>The
<dfn method for=ServiceWorkerRegistration><code>getNotifications(<var>filter</var>)</code></dfn>
method, when invoked, must run these steps:

<ol>
  <li><p>Let <var>promise</var> be a new promise.

  <li><p>Run these steps <a>in parallel</a>:

  <ol>
    <li><p>Let <var>tag</var> be <var>filter</var>'s <code>tag</code>.

    <li><p>Let <var>notifications</var> be a <a for=/>list</a> of all <a>notifications</a> in the
    <a>list of notifications</a> whose <a for=notification>origin</a> is the
    <a>entry settings object</a>'s <a for="environment settings object">origin</a>, whose
    <a for=notification>service worker registration</a> is the <a>context object</a>, and whose
    <a for=notification>tag</a>, if <var>tag</var> is not the empty string, is <var>tag</var>.

    <li><p>Let <var>objects</var> be an empty JavaScript array.

    <li><p><a for=list>For each</a> <a>notification</a> in
    <var>notifications</var>, in creation order, create a new {{Notification}}
    object representing <a>notification</a> and push
    that object to <var>objects</var>.

    <li><p>Resolve <var>promise</var> with <var>objects</var>.
  </ol>

  <li><p>Return <var>promise</var>.
</ol>

<p class=note>This method returns zero or more new {{Notification}} objects which might represent
the same underlying <a>notification</a> of {{Notification}} objects already in existence.

<hr>

<p>To <dfn>fire a service worker notification event named <var>e</var></dfn>
given <var>notification</var> and <var>action</var>,
<a>fire an event</a> named <var>e</var>, using {{NotificationEvent}}, with the
{{NotificationEvent/notification}} attribute initialized to a new
{{Notification}} object representing <var>notification</var> and the
{{NotificationEvent/action}} attribute initialized to <var>action</var>.
<!-- XXX need to define at what the event is fired -->

<p>The {{NotificationEvent/notification}} attribute's getter must return the
value it was initialized to.

<p>The {{NotificationEvent/action}} attribute's getter must return the value it
was initialized to.

<p>The following is the <a>event handler</a> (and its corresponding
<a>event handler event type</a>) that must be supported as attribute by the
{{ServiceWorkerGlobalScope}} object:

<table>
  <thead>
    <tr>
      <th><a>event handler</a>
      <th><a>event handler event type</a>
  <tbody>
    <tr>
      <td><dfn attribute for=ServiceWorkerGlobalScope><code>onnotificationclick</code></dfn>
      <td><code>notificationclick</code>
    <tr>
      <td><dfn attribute for=ServiceWorkerGlobalScope><code>onnotificationclose</code></dfn>
      <td><code>notificationclose</code>
</table>


<h2 id=acknowledgments class=no-num>Acknowledgments</h2>

<p>Thanks to
Addison Phillips,
Aharon (Vladimir) Lanin,
Alex Russell,
Anssi Kostiainen,
Arkadiusz Michalski,
Boris Zbarsky,
David Håsäther,
Doug Turner,
Drew Wilson,
Ehsan Akhgari,
Frederick Hirsch,
Ian Hickson,
Jake Archibald,
James Graham,
John Mellor,
Jon Lee,
Jonas Sicking,
Michael Cooper,
Michael Henretty,
Michael™ Smith,
Michael van Ouwerkerk,
Nicolás Satragno,
Olli Pettay,
Peter Beverloo,
Philip Jägenstedt,
Reuben Morais,
Rich Tibbett,
Robert Bindar,
박상현 (Sanghyun Park),
Simon Pieters,
Theresa O'Connor,
timeless, and
triple-underscore
for being awesome.

<p>This standard is written by
<a lang=nl href=https://annevankesteren.nl/>Anne van Kesteren</a>
(<a href=https://www.mozilla.org/>Mozilla</a>,
<a href=mailto:annevk@annevk.nl>annevk@annevk.nl</a>). An earlier iteration was written
by John Gregg (<a href=https://www.google.com/>Google</a>,
<a href=mailto:johnnyg@google.com>johnnyg@google.com</a>).

<pre class="anchors">
urlPrefix: https://html.spec.whatwg.org/multipage/
    urlPrefix: webappapis.html; type: dfn
        text: entry settings object
urlPrefix: https://w3c.github.io/ServiceWorker/; type: dfn
    text: handle functional event; url:handle-functional-event-algorithm
urlPrefix: https://w3c.github.io/vibration/
    urlPrefix: #dfn-; type: dfn
        text: perform vibration
        text: validate and normalize
    urlPrefix: #idl-def-; type: interface
        text: VibratePattern; url: vibratepattern
urlPrefix: https://tc39.github.io/ecma262/#sec-object.; type: dfn
    text: freeze
</pre>

<pre class="biblio">
{
    "LANG": {
        "aliasOf" : "BCP47"
    }
}
</pre>