windows.onFocusChanged

Fired when the currently focused window changes. Will be windows.WINDOW_ID_NONE if all browser windows have lost focus.

Note: In Windows and some Linux window managers, WINDOW_ID_NONE will always be sent immediately preceding a switch from one browser window to another.

Syntax

browser.windows.onFocusChanged.addListener(listener)
browser.windows.onFocusChanged.removeListener(listener)
browser.windows.onFocusChanged.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 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:

windowId: integer. ID of the newly focused window.

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`onFocusChanged`	Yes	14	45	?	Yes	14	?	?	No	?	15 Fires when toggling in or out of private browsing mode, leaving Safari to the home screen, and returning to Safari from the home screen.	?

Examples

Log focus changes:

browser.windows.onFocusChanged.addListener((windowId) => {
  console.log(`Newly focused window: ${windowId}`);
});

Example extensions

bookmark-it

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

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/windows/onFocusChanged