Notifications API ( PR #132 )

1. Terminology

This specification depends on the Infra Standard. [INFRA]

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]

2. Notifications

A notification is an abstract representation of something that happened, such as the delivery of a message.

A notification can have an associated service worker registration .

A notification has an associated title which is a DOMString.

A notification has an associated body which is a DOMString.

A notification has an associated direction which is one of auto , ltr , and rtl .

A notification has an associated language which is a DOMString representing either a valid BCP 47 language tag or the empty string.

A notification has an associated tag which is a DOMString.

A notification has an associated data .

A notification has an associated timestamp 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.

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.

A notification has an associated origin .

A notification has an associated renotify preference flag which is initially unset. When set indicates that the end user should be alerted after the replace steps have run.

A notification has an associated silent preference flag which is initially unset. When set indicates that no sounds or vibrations should be made.

A notification has an associated require interaction preference flag 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.

A notification can have these associated graphics: an image URL , icon URL , and badge URL ; and their corresponding image resource , icon resource , and badge resource .

An image resource is a picture shown as part of the content of the notification , and should be displayed with higher visual priority than the icon resource and badge resource , though it may be displayed in fewer circumstances.

An icon resource is an image that reinforces the notification (such as an icon, or a photo of the sender).

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

A notification can have a vibration pattern .

Developers are encouraged to not convey information through an image , icon , badge , or vibration pattern that is not otherwise accessible to the end user, especially since notification platforms that do not support these features might ignore them.

A notification has an associated action list (a list of zero actions ). It is initially empty.

An action defines a way the user can interact with a notification, as an alternative to activing the notification itself.

The user agent must determine the maximum number of actions supported, within the constraints of the notification platform.

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. The ability to reply inline to notifications during activation is also platform-dependent, so developers are encouraged to handle the case where a text action was activated but the reply was null (e.g., by focusing a chat window).

Some platforms might modify an icon resource 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.

A non-persistent notification is a notification without an associated service worker registration .

A persistent notification is a notification with an associated service worker registration .

To create a notification , given a title , options , and optionally a serviceWorkerRegistration , run these steps:

1. Let notification be a new notification .

2. If a serviceWorkerRegistration was provided, set notification ’s service worker registration to serviceWorkerRegistration .

3. If a serviceWorkerRegistration was not provided and options ’s actions is not empty, then throw a TypeError exception. .

   Actions are only currently supported for persistent notifications .

4. If options ’s silent is true and options ’s vibrate is present, throw a TypeError exception.

5. If options ’s renotify is true and options ’s tag is the empty string, throw a TypeError exception.

6. Set notification ’s data to StructuredSerializeForStorage ( options ’s data ). Rethrow any exceptions.

7. Set notification ’s title to title .

8. Set notification ’s direction to options ’s dir .

9. Set notification ’s language to options ’s lang .

10. Set notification ’s origin to the entry settings object ’s origin .

11. Set notification ’s body to options ’s body .

12. Set notification ’s tag to options ’s tag .

13. Let baseURL be the API base URL specified by the entry settings object . Or incumbent?

14. If options ’s image is present, parse it using baseURL , and if that does not return failure, set notification ’s image URL to the return value. (Otherwise image URL is not set.)

15. If options ’s icon is present, parse it using baseURL , and if that does not return failure, set notification ’s icon URL to the return value. (Otherwise icon URL is not set.)

16. If options ’s badge is present, parse it using baseURL , and if that does not return failure, set notification ’s badge URL to the return value. (Otherwise badge URL is not set.)

17. If options ’s vibrate is present, validate and normalize it and set notification ’s vibration pattern to the return value. (Otherwise vibration pattern is not set.)

18. If options ’s timestamp is present, set notification ’s timestamp to the value. Otherwise, set notification ’s timestamp to the number of milliseconds that passed between 00:00:00 UTC on 1 January 1970 and the time at which the Notification constructor was called.

19. If options ’s renotify is true, set notification ’s renotify preference flag .

20. If options ’s silent is true, set notification ’s silent preference flag .

21. If options ’s requireInteraction is true, set notification ’s require interaction preference flag .

22. Set notification ’s list of actions to an empty list, then for For each entry in options ’s actions , up to :

    1. If the maximum number of actions supported (skip any excess entries), perform the following steps: has already been added, then break.

    2. Let action be a new action .

    3. Set action ’s type to entry ’s type member.

    4. Set action ’s name to the entry ’s action .

    5. Set action ’s title to the entry ’s title .

    6. If entry ’s icon is present, parse it using baseURL , and if that does not return failure, set action ’s icon URL to the return value. (Otherwise icon URL

    7. If entry ’s placeholder is not set.) present, then set action’s placeholder to the entry ’s placeholder .

    8. Append action to notification ’s action list of actions .

23. Return notification .

2.1. Lifetime and UI integration

The user agent must keep a list of notifications , which is a list of zero or more notifications .

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

User agents should not display non-persistent notification in a platform’s "notification center" (if available).

User agents should persist persistent notifications until they are removed from the list of notifications .

A persistent notification could have the close() method invoked of one of its Notification objects.

User agents should display persistent notifications in a platform’s "notification center" (if available).

2.2. Permission model

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

" default "

This is equivalent to " denied ", but the user has made no explicit choice thus far.

" denied "

This means the user does not want notifications .

" granted "

This means notifications can be displayed.

There is no equivalent to " default " meaning " granted ". In that case " granted " is simply returned as there would be no reason for the application to ask for permission .

2.3. Direction

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

User agents are expected to honor the Unicode semantics of the text of a notification ’s title , body , and the title of each of its actions . 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 title , body and the title of each of the actions , the notification ’s direction provides the higher-level override of rules P2 and P3 if it has a value other than " auto ". [BIDI]

The notification ’s direction also determines the relative order in which the notification ’s actions should be displayed to the user, if the notification platform displays them side by side.

2.4. Language

The notification ’s language specifies the primary language for the notification ’s title , body and the title of each of its actions . 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]

Developers are encouraged to only use valid language tags.

2.5. Resources

The fetch steps for a given notification notification are:

1. If the notification platform supports images, fetch notification ’s image URL , if image URL is set.

   The intent is to fetch this resource similar to an <img> , but this needs abstracting .

   Then, in parallel :

   1. Wait for the response .

   2. If the response ’s internal response ’s type is " default ", then attempt to decode the resource as image.

   3. If the image format is supported, set notification ’s image resource to the decoded resource. (Otherwise notification has no image resource .)

2. If the notification platform supports icons, fetch notification ’s icon URL , if icon URL is set.

   The intent is to fetch this resource similar to an <img> , but this needs abstracting .

   Then, in parallel :

   1. Wait for the response .

   2. If the response ’s internal response ’s type is " default ", then attempt to decode the resource as image.

   3. If the image format is supported, set notification ’s icon resource to the decoded resource. (Otherwise notification has no icon resource .)

3. If the notification platform supports badges, fetch notification ’s badge URL , if badge URL is set.

   The intent is to fetch this resource similar to an <img> , but this needs abstracting .

   Then, in parallel :

   1. Wait for the response .

   2. If the response ’s internal response ’s type is " default ", then attempt to decode the resource as image.

   3. If the image format is supported, set notification ’s badge resource to the decoded resource. (Otherwise notification has no badge resource .)

4. If the notification platform supports actions and action icons, then for each action in notification ’s action list of actions : fetch action ’s icon URL , if icon URL is set.

   The intent is to fetch this resource similar to an <img> , but this needs abstracting .

   Then, in parallel :

   1. Wait for the response .

   2. If the response ’s internal response ’s type is " default ", then attempt to decode the resource as image.

   3. If the image format is supported, set action ’s icon resource to the decoded resource. (Otherwise action has no icon resource .)

2.6. Showing a notification

The show steps for a given notification notification are:

1. Wait for any fetches to complete and notification ’s image resource icon resource , and badge resource to be set (if any), as well as the icon resources for the notification ’s actions (if any).

2. Let shown be false.

3. Let oldNotification be the notification in the list of notifications whose tag is not the empty string and is notification ’s tag , and whose origin is same origin with notification ’s origin , if any, and null otherwise.

4. If oldNotification is non-null, then:

   1. Handle close events with oldNotification .

   2. If the notification platform supports replacement, then:

      1. Replace oldNotification with notification , in the list of notifications .

      2. Set shown to true.

      Notification platforms are strongly encouraged to support native replacement as it leads to a better user experience.

   3. Otherwise, remove oldNotification from the list of notifications .

5. If shown is false, then:

   1. Append notification to the list of notifications .

   2. Display notification on the device (e.g., by calling the appropriate notification platform API).

   If the platform does not support entering text within a notification, implementers are expected to present text actions as button actions.

6. If shown is false or oldNotification is non-null and notification ’s renotify preference flag has been set, then run the alert steps for notification .

7. If notification is a non-persistent notification , then queue a task to fire an event named show on the Notification object representing notification .

User agents are required to attribute notifications to the origin they are associated with. This reduces the possibility of phishing attacks where a notification has been designed to look like it originates from another origin. The user should be aware that data entered into the notification will be made available to the attributed origin.

2.7. Activating a notification

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

1. If notification is a persistent notification , then:

   1. Let action be the empty string.

   2. Let reply be null.

   3. If one of notification ’s actions was activated by the user, then set action to that action ’s name .

   4. If one of notification ’s actions with type text was activated by the user, and the opportunity to input a reply was provided, then set reply to the text entered by the user during activation.

   5. Let callback be an algorithm that when invoked with a global , fires a service worker notification event named notificationclick given notification , action and action reply on global .

   6. Then run Handle Functional Event with notification ’s service worker registration and callback .

2. Otherwise, queue a task to run these steps:

   1. Let intoFocus be the result of firing an event named click on the Notification object representing notification , with its cancelable attribute initialized to true.

      User agents are encouraged to make focus() work from within the event listener for the event named click .

   2. If intoFocus is true, then the user agent should bring the notification ’s related browsing context ’s viewport into focus.

Throughout the web platform "activate" is intentionally misnamed as "click".

2.8. Closing a notification

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

The close steps for a given notification are:

1. If the list of notifications does not contain notification , then abort these steps.

2. Handle close events with notification .

3. Remove notification from the list of notifications .

To handle close events given a notification , run these steps:

1. If notification is a persistent notification and notification was closed by the user, then:

   1. Let callback be an algorithm that when invoked with a global , fires a service worker notification event named notificationclose given notification , action set to the empty string and reply set to null on global .

   2. Then run Handle Functional Event with notification ’s service worker registration and callback .

2. If notification is a non-persistent notification , then queue a task to fire an event named close on the Notification object representing notification .

2.9. Alerting the user

The alert steps for alerting the user about a given notification are:

1. Perform vibration using notification ’s vibration pattern , if any.

3. API

[Constructor(DOMString title, optional NotificationOptions options),
 Exposed=(Window,Worker)]
interface Notification : EventTarget {
  static readonly attribute NotificationPermission permission;
  [Exposed=Window] static Promise<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;
  [SameObject] readonly attribute FrozenArray<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<NotificationAction> actions;
  void close();
};
dictionary NotificationOptions {
  NotificationDirection dir = "auto";
  DOMString lang = "";
  DOMString body = "";
  DOMString tag = "";
  USVString image;
  USVString icon;
  USVString badge;
  VibratePattern vibrate;
  DOMTimeStamp timestamp;
  boolean renotify = false;
  boolean silent = false;
  boolean requireInteraction = false;
  any data = null;
  sequence<NotificationAction> actions = [];
};
enum NotificationPermission {
  "default",
  "denied",
  "granted"
};
enum NotificationDirection {
  "auto",
  "ltr",
  "rtl"
};
dictionary NotificationAction {
  NotificationActionType type = "button";
  required DOMString action;
  required DOMString title;
  USVString icon;
  DOMString? placeholder = "";
};
enum NotificationActionType {  "button",  "text"
};
callback NotificationPermissionCallback = void (NotificationPermission permission);

A non-persistent notification is represented by one Notification object and can be created through Notification 's constructor .

A persistent notification is represented by zero or more Notification objects and can be created through the showNotification() method.

3.1. Garbage collection

A Notification object must not be garbage collected while the list of notifications contains its corresponding notification and it has an event listener whose type is click , show , close , or error .

3.2. Constructors

The Notification(title, options) constructor, when invoked, must run these steps:

1. If the current global object is a ServiceWorkerGlobalScope object, then throw a TypeError exception.

2. Let notification be the result of creating a notification given title and options . Rethrow any exceptions.

3. Let n be a new Notification object associated with notification .

4. Run these steps in parallel :

   1. If permission for notification ’s origin is not " granted ", then queue a task to fire an event named error on n , and abort these steps.

   2. Run the fetch steps for notification .

   3. Run the show steps for notification .

5. Return n .

3.3. Static members

The static permission attribute’s getter must return permission for the entry settings object ’s origin .

If you edit standards please refrain from copying the above. Synchronous permissions are like synchronous IO, a bad idea.

The static requestPermission( deprecatedCallback ) method, when invoked, must run these steps:

1. Let promise be a new promise.

2. Run these steps in parallel :

   1. Let permission be permission for entry settings object ’s origin .

   2. If permission is " default ", ask the user whether showing notifications for the entry settings object ’s origin is acceptable. If it is, set permission to " granted ", and " denied " otherwise.

   3. Queue a task to run these steps:

      1. Set permission for the entry settings object ’s origin to permission .

      2. If deprecatedCallback is given, invoke deprecatedCallback with permission as single argument. If this throws an exception, report the exception .

      3. Fullfil promise with permission .

3. Return promise .

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 many more suitable alternatives .

The static maxActions attribute’s getter must return the maximum number of actions supported.

3.4. Object members

The following are the event handlers (and their corresponding event handler event types ) that must be supported as attributes by the Notification object.

The close() method, when invoked, must run the close steps for the notification .

The title attribute’s getter must return the notification ’s title .

The dir attribute’s getter must return the notification ’s direction .

The lang attribute’s getter must return the notification ’s language .

The body attribute’s getter must return the notification ’s body .

The tag attribute’s getter must return the notification ’s tag .

The image attribute’s getter must return the notification ’s image URL , serialized , and the empty string if there is no notification ’s image URL otherwise.

The icon attribute’s getter must return the notification ’s icon URL , serialized , and the empty string if there is no notification ’s icon URL otherwise.

The badge attribute’s getter must return the notification ’s badge URL , serialized , and the empty string if there is no notification ’s badge URL otherwise.

The vibrate attribute’s getter must return the notification ’s vibration pattern , if any, and the empty list otherwise.

The timestamp attribute’s getter must return the notification ’s timestamp .

The renotify attribute’s getter must return the notification ’s renotify preference flag .

The silent attribute’s getter must return the notification ’s silent preference flag .

The requireInteraction attribute’s getter must return the notification ’s require interaction preference flag .

The data attribute’s getter must return StructuredDeserialize ( notification ’s data , context object ’s relevant Realm ). If this throws an exception, then return null.

The actions attribute’s getter must return the result of the following steps:

1. Let frozenActions be an empty list of type NotificationAction .

2. For each entry in the notification ’s action list of actions , perform the following steps: :

   1. Let action be a new NotificationAction .

   2. Set action ’s type to entry ’s type .

   3. Set action ’s action to entry ’s name .

   4. Set action ’s title to entry ’s title .

   5. Set action ’s icon to entry ’s icon URL .

   6. Set action ’s placeholder to entry ’s placeholder .

   7. Call Object.freeze on action , to prevent accidental mutation by scripts.

   8. Append action to frozenActions .

3. Create a frozen array from frozenActions .

3.5. Examples

3.5.1. Using events from a page

Non-persistent Notification objects dispatch events during their lifecycle, which developers can use to generate desired behaviors.

The click event dispatches when the user activates a notification.

var not = new Notification("Gebrünn Gebrünn by Paul Kalkbrenner", { icon: "newsong.svg", tag: "song" });
not.onclick
=
function()
{
displaySong(this);
};

3.5.2. Using actions from a service worker

Persistent notifications fire notificationclick events on the ServiceWorkerGlobalScope .

Here a service worker shows a notification with a single "Archive" action , 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.

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);

3.5.3. Using the tag member for multiple instances

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 tag member.

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.

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'
});

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

3.5.4. Using the tag member for a single instance

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

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.

// 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'
});

The result of this situation is a single 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 close() method.

4. Service worker API

dictionary GetNotificationOptions {
   = "";

  DOMString tag = "";
};
partial interface ServiceWorkerRegistration {
  );

  Promise<void> showNotification(DOMString title, optional NotificationOptions options);
  Promise<sequence<Notification>> getNotifications(optional GetNotificationOptions filter);
};
[),

[Constructor(DOMString type, NotificationEventInit eventInitDict),

 Exposed=ServiceWorker]
interface NotificationEvent : ExtendableEvent {
  readonly attribute Notification notification;
  ;

  readonly attribute DOMString action;
  readonly attribute DOMString? reply;
};
dictionary NotificationEventInit : ExtendableEventInit {
  required Notification notification;
   = "";

  DOMString action = "";
  DOMString? reply = null;
};
partial interface ServiceWorkerGlobalScope {
  attribute EventHandler onnotificationclick;
  attribute EventHandler onnotificationclose;
};

The showNotification(title, options) method, when invoked, must run these steps:

1. Let promise be a new promise.

2. If the context object ’s active worker is null, then reject promise with a TypeError exception and return promise .

3. Let serviceWorkerRegistration be the context object .

4. Let notification be the result of creating a notification given title , options , and serviceWorkerRegistration . If this threw an exception, reject promise with that exception and return promise .

5. Run these steps in parallel :

   1. If permission for notification ’s origin is not " granted ", then reject promise with a TypeError exception, and abort these steps.

   2. Run the fetch steps for notification .

   3. Run the show steps for notification .

   4. Resolve promise with undefined.

6. Return promise .

The getNotifications( filter ) method, when invoked, must run these steps:

1. Let promise be a new promise.

2. Run these steps in parallel :

   1. Let tag be filter ’s tag .

   2. Let notifications be a list of all notifications in the list of notifications whose origin is the entry settings object ’s origin , whose service worker registration is the context object , and whose tag , if tag is not the empty string, is tag .

   3. Let objects be an empty JavaScript array.

   4. For each notification in notifications , in creation order, create a new Notification object representing notification and push that object to objects .

   5. Resolve promise with objects .

3. Return promise .

This method returns zero or more new Notification objects which might represent the same underlying notification of Notification objects already in existence.

To fire a service worker notification event named e given notification , action and action reply , fire an event named e , using NotificationEvent , with the notification attribute initialized to a new Notification object representing notification and , the action attribute initialized to action , and the reply attribute initialized to reply .

The notification attribute’s getter must return the value it was initialized to.

The action attribute’s getter must return the value it was initialized to.

The reply attribute’s getter must return the value it was initialized to.

The following is the event handler (and its corresponding event handler event type ) that must be supported as attribute by the ServiceWorkerGlobalScope object:

Acknowledgments

Thanks to Addison Phillips, Aharon (Vladimir) Lanin, Alex Russell, Anita Woodruff, 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.

This standard is written by Anne van Kesteren ( Mozilla , annevk@annevk.nl ). An earlier iteration was written by John Gregg ( Google , johnnyg@google.com ).

Copyright © 2018 WHATWG (Apple, Google, Mozilla, Microsoft). This work is licensed under a Creative Commons Attribution 4.0 International License .