windows.getLastFocused()

Gets the window that was most recently focused — typically the window 'on top'.

This is an asynchronous function that returns a Promise.

getInfoOptional

object.

populateOptional

boolean. If true, the windows.Window object will have a tabs property that contains a list of tabs.Tab objects representing the tabs in the window. The Tab objects only contain the url, title and favIconUrl properties if the extension's manifest file includes the "tabs" permission or host permissions matching the tab's URL.

windowTypesOptional

An array of windows.WindowType objects. If set, the windows.Window returned will be filtered based on its type. If unset the default filter is set to ['normal', 'panel', 'popup'], with 'panel' window types limited to the extension's own windows.

A Promise that will be fulfilled with a windows.Window object containing the details of the last focused window. If any error occurs, the promise will be rejected with an error message.

Get the last focused window, and log the tabs it contains. Note that you'll need the "tabs" permission or matching host permissions to access tab URLs.

function logTabs(windowInfo) {
  for (tabInfo of windowInfo.tabs) {
    console.log(tabInfo.url);
  }
}

function onError(error) {
  console.log(`Error: ${error}`);
}

browser.browserAction.onClicked.addListener((tab) => {
  var getting = browser.windows.getLastFocused({populate: true});
  getting.then(logTabs, onError);
});