index.md

---

title: notifications.onShown
slug: Mozilla/Add-ons/WebExtensions/API/notifications/onShown
page-type: webextension-api-event
tags:
  - API
  - Add-ons
  - Event
  - Extensions
  - Notifications
  - Reference
  - WebExtensions
  - events
  - onShown
browser-compat: webextensions.api.notifications.onShown

---

{{AddonSidebar()}}

Fired immediately after a notification has been shown.

Syntax

browser.notifications.onShown.addListener(listener)
browser.notifications.onShown.removeListener(listener)
browser.notifications.onShown.hasListener(listener)

Events have three functions:

• addListener(callback)

  • : Adds a listener to this event.

• removeListener(listener)

  • : Stop listening to this event. The listener argument is the listener to remove.

• hasListener(listener)

  • : Check whether listener is registered for this event. Returns true if it is listening, false otherwise.

addListener syntax

Parameters

• callback

  • : Function that will be called when this event occurs. The function will be passed the following arguments:

    • notificationId

      • : string. ID of the notification that has been shown.

Browser compatibility

{{Compat}}

Examples

Add a listener to the {{WebExtAPIRef("notifications.onShown")}} event and log its details:

function logShown(itemId) {
  console.log(`shown: ${itemId}`);
  browser.notifications.getAll().then((all) => {
    console.log(all[itemId]);
  })
}

browser.notifications.onShown.addListener(logShown);

{{WebExtExamples}}

Note: This API is based on Chromium's chrome.notifications API.