index.md

---

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

---

{{AddonSidebar()}}

Fired when an update to the extension is available. This event enables an extension to delay an update: for example, because it is in the middle of some operation which should not be interrupted.

If the extension is not listening for this event when an update becomes available, the extension is reloaded immediately and the update is applied. If the extension is listening, then the update will be applied the next time the extension is reloaded. This happens if:

• the browser is restarted

• the extension is disabled and re-enabled

• the extension explicitly reloads itself by calling {{WebExtAPIRef('runtime.reload()')}}.

Syntax

browser.runtime.onUpdateAvailable.addListener()
browser.runtime.onUpdateAvailable.removeListener(listener)
browser.runtime.onUpdateAvailable.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)

  • : Checks whether a 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:

    • details

      • : object. Contains a single property, a string named version, which represents the version number of the update.

Browser compatibility

{{Compat}}

Examples

Listen for UpdateAvailable events:

function handleUpdateAvailable(details) {
  console.log(details.version);
  // Proceed to upgrade the add-on
  browser.runtime.reload();
}

browser.runtime.onUpdateAvailable.addListener(handleUpdateAvailable);

{{WebExtExamples}}

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