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tabs.onActivated

files/en-us/mozilla/add-ons/webextensions/api/tabs/onactivated/index.md

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Fires when the active 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

js-nolint
browser.tabs.onActivated.addListener(listener)
browser.tabs.onActivated.removeListener(listener)
browser.tabs.onActivated.hasListener(listener)

Events have three functions:

  • addListener(listener)
    • : 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

  • listener
    • : The function called when this event occurs. The function is passed this argument:
      • activeInfo
        • : object. ID of the tab that was made active, and ID of its window. See the activeInfo section for more details.

Additional objects

activeInfo

  • previousTabId
    • : integer. The ID of the previous activated tab, if that tab is still open.
  • tabId
    • : integer. The ID of the tab that has become active.
  • windowId
    • : integer. The ID of the tab's window.

Examples

Listen for and log tab activation events:

js
function handleActivated(activeInfo) {
  console.log(`Tab ${activeInfo.tabId} was activated`);
}

browser.tabs.onActivated.addListener(handleActivated);

{{WebExtExamples}}

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.

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