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GitHub Repository: mohamedkhallouq/content
 Path: blob/main/files/en-us/mozilla/add-ons/webextensions/api/runtime/onstartup/index.md
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---
title: runtime.onStartup
slug: Mozilla/Add-ons/WebExtensions/API/runtime/onStartup
page-type: webextension-api-event
tags:
  - API
  - Add-ons
  - Event
  - Extensions
  - Non-standard
  - Reference
  - WebExtensions
  - onStartup
  - runtime
browser-compat: webextensions.api.runtime.onStartup
---

{{AddonSidebar()}}

Fired when a profile that has this extension installed first starts up. This event is not fired when a private browsing/incognito profile is started, even if this extension is operating in 'split' incognito mode.

Syntax

browser.runtime.onStartup.addListener(listener)
browser.runtime.onStartup.removeListener(listener)
browser.runtime.onStartup.hasListener(listener)

Event Functions

All events have three functions:

  • addListener(listener)

    • : Adds a listener to the calling event.

  • removeListener(listener)

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

  • hasListener(listener)

    • : Checks whether a listener is registered for the calling event. Returns true if it is listening, false otherwise.

Parameters

The only parameter is listener, used for any of the above functions.

  • listener

    • : A function that will be called when this event occurs.

Browser compatibility

{{Compat}}

Examples

Open https://giphy.com/explore/cat when the browser starts up:

function handleStartup() {
  browser.tabs.create({
    url: "https://giphy.com/explore/cat"
  });
}

browser.runtime.onStartup.addListener(handleStartup);

{{WebExtExamples}}

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