The OnChangedCause type of the cookies API represents the reason a cookie changed.


Values of this type are strings. Possible values are:


A cookie has been automatically removed due to garbage collection.


A cookie has been automatically removed due to expiry.


A cookie has been inserted or removed via an explicit call to cookies.remove().


A cookie has been overwritten by a cookie with an already-expired expiration date.


A call to cookies.set() overwrote this cookie with a different one.

Browser compatibility

BCD tables only load in the browser


You can listen to the cookies.onChanged event to be notified when cookies change. The listener is passed a changeInfo object that contains a cause property, whose value is the OnChangeCaused string:

browser.cookies.onChanged.addListener((changeInfo) => {
  console.log(`Cookie changed: \n`
    + ` * Cookie: ${JSON.stringify(changeInfo.cookie)}\n`
    + ` * Cause: ${changeInfo.cause}\n`
    + ` * Removed: ${changeInfo.removed}`);

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

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