index.md

---

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

---

{{AddonSidebar()}}

Fired when a tab is created.

Note that the tab's URL may not be given its final value at the time this event fired. In particular, Firefox opens a new tab with the URL "about:blank" before loading the new page into it. You can listen to {{WebExtAPIRef("tabs.onUpdated")}} events to be notified when a URL is set.

Syntax

browser.tabs.onCreated.addListener(callback)
browser.tabs.onCreated.removeListener(listener)
browser.tabs.onCreated.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:

    • tab

      • : {{WebExtAPIRef('tabs.Tab')}}. Details of the tab that was created.

Examples

Log the IDs of newly created tabs:

function handleCreated(tab) {
  console.log(tab.id);
}

browser.tabs.onCreated.addListener(handleCreated);

{{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.