index.md

---

title: tabs.onActiveChanged
slug: Mozilla/Add-ons/WebExtensions/API/tabs/onActiveChanged
page-type: webextension-api-event
tags:
  - API
  - Add-ons
  - Deprecated
  - Event
  - Extensions
  - Non-standard
  - Reference
  - WebExtensions
  - onActiveChanged
  - tabs
browser-compat: webextensions.api.tabs.onActiveChanged

---

{{AddonSidebar()}}

Warning: This event is deprecated. Use {{WebExtAPIRef("tabs.onActivated")}} instead.

Fires when the selected tab in a window changes. Note that the tab's URL may not be set at the time this event fired, but you can listen to {{WebExtAPIRef('tabs.onUpdated')}} events to be notified when a URL is set.

Syntax

browser.tabs.onActiveChanged.addListener(listener)
browser.tabs.onActiveChanged.removeListener(listener)
browser.tabs.onActiveChanged.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:

    • tabId

      • : integer. The ID of the tab that has become active.

    • selectInfo

      • : object. See the selectInfo section for more details.

Additional objects

selectInfo

• windowId

  • : integer. The ID of the window containing the selected tab.

Browser compatibility

{{Compat}}

Note: This API is based on Chromium's chrome.tabs API. This documentation is derived from tabs.json in the Chromium code.