sessions.onChanged

Fired whenever the list of closed tabs or windows changes.

Syntax

browser.sessions.onChanged.addListener(listener)
browser.sessions.onChanged.removeListener(listener)
browser.sessions.onChanged.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. It's passed no parameters.

Browser compatibility

Chrome Edge Firefox Firefox for Android Opera
Basic support Yes No 53.0 No 33

Examples

This very annoying add-on listens for onChanged, then immediately restores the most recently closed session, thus making it impossible to close windows or tabs:

function restoreSession(sessionInfos) {
  if (!sessionInfos.length) {
    console.log("No sessions found")
    return;
  }
  let sessionInfo = sessionInfos[0];
  if (sessionInfo.tab) {
    browser.sessions.restore(sessionInfo.tab.sessionId);
  } else {
    browser.sessions.restore(sessionInfo.window.sessionId);
  }
}

function onError(error) {
  console.log(error);
}

function restoreMostRecent() {
  var gettingSessions = browser.sessions.getRecentlyClosed({
    maxResults: 1
  });
  gettingSessions.then(restoreSession, onError);
}

browser.sessions.onChanged.addListener(restoreMostRecent);

Acknowledgements

This API is based on Chromium's chrome.tabs API.

Microsoft Edge compatibility data is supplied by Microsoft Corporation and is included here under the Creative Commons Attribution 3.0 United States License.

Document Tags and Contributors

 Contributors to this page: wbamberg
 Last updated by: wbamberg,