Notification.tag

The tag read-only property of the Notification interface signifies an identifying tag for the notification, as specified in the tag option of the Notification() constructor.

The idea of notification tags is that more than one notification can share the same tag, linking them together. One notification can then be programmatically replaced with another to avoid the users' screen being filled up with a huge number of similar notifications.

Note: This feature is available in Web Workers.

Syntax

var tag = Notification.tag;

Value

A DOMString.

Examples

Our Using the Notifications API article has a good example of tag usage.

Specifications

Specification	Status	Comment
Notifications API The definition of 'tag' in that specification.	Living Standard	Living standard

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari
Basic support	5 webkit (see notes) 22	4.0 moz (see notes) 22	Not supported	25	6 (see notes)
Available in workers	?	41.0 (41.0)	?	?	?

Feature	Android	Android Webview	Firefox Mobile (Gecko)	Firefox OS	IE Mobile	Opera Mobile	Safari Mobile	Chrome for Android
Basic support	?	(Yes)	4.0 moz (see notes) 22	1.0.1 moz (see notes) 1.2	Not supported	?	Not supported	(Yes)
Available in workers	?	?	41.0 (41.0)	?	?	?	?	?

Firefox OS notes

Prior to Firefox 22 (Firefox OS <1.2), the instantiation of a new notification must be done with the navigator.mozNotification object through its createNotification method.
Prior to Firefox 22 (Firefox OS <1.2), the Notification was displayed when calling the show method and supported only the click and close events.
Nick Desaulniers wrote a Notification shim to cover both newer and older implementations.
One particular Firefox OS issue is that you can pass a path to an icon to use in the notification, but if the app is packaged you cannot use a relative path like /my_icon.png. You also can't use window.location.origin + "/my_icon.png" because window.location.origin is null in packaged apps. The manifest origin field fixes this, but it is only available in Firefox OS 1.1+. A potential solution for supporting Firefox OS <1.1 is to pass an absolute URL to an externally hosted version of the icon. This is less than ideal as the notification is displayed immediately without the icon, then the icon is fetched, but it works on all versions of Firefox OS.
When using notifications in a Firefox OS app, be sure to add the desktop-notification permission in your manifest file. Notifications can be used at any permission level, hosted or above.
```
"permissions": {
    "desktop-notification":{}
}
```

Chrome notes

Before Chrome 22, the support for notification followed an old prefixed version of the specification and used the navigator.webkitNotifications object to instantiate a new notification.
Before Chrome 32, Notification.permission was not supported.
Before Chrome 42, service worker additions were not supported.

Safari notes

Safari started to support notification with Safari 6, but only on Mac OSX 10.8+ (Mountain Lion).