storage.onChanged
Fires when one or more items in any of the storage areas changes.
If you only need to listen for changes in one storage area, use storage.StorageArea.onChanged instead.
Fired when storageArea.set, storageArea.remove, or storageArea.clear executes against any of the storage areas.
Note:
In Firefox, the listener receives all the keys from a storage area where storageArea.set executes. The listener may be invoked when there is no change to the data. To find details of the changed items, examine each key's storage.StorageChange object. See Firefox bug 1833153.
Note:
Firefox does not fire this event for changes to storage.managed because managed storage is only read on browser startup (from the JSON manifest (native manifest) file or 3rdparty enterprise policy).
Syntax
browser.storage.onChanged.addListener(listener)
browser.storage.onChanged.removeListener(listener)
browser.storage.onChanged.hasListener(listener)
Events have three functions:
addListener(listener)-
Adds a listener to this event.
removeListener(listener)-
Stop listening to this event. The
listenerargument is the listener to remove. hasListener(listener)-
Check whether
listeneris registered for this event. Returnstrueif it is listening,falseotherwise.
addListener syntax
Parameters
listener-
The function called when this event occurs. The function is passed these arguments:
changes-
object. Object describing the change. The name of each property is the name of each key. The value of each key is astorage.StorageChangeobject describing the change to that item. areaName-
string. The name of the storage area ("local","managed","session", or"sync") to which the changes were made.
Examples
/*
Log the storage area that changed,
then for each item changed,
log its old value and its new value.
*/
function logStorageChange(changes, area) {
console.log(`Change in storage area: ${area}`);
const changedItems = Object.keys(changes);
for (const item of changedItems) {
console.log(`${item} has changed:`);
console.log("Old value: ", changes[item].oldValue);
console.log("New value: ", changes[item].newValue);
}
}
browser.storage.onChanged.addListener(logStorageChange);
Example extensions
Browser compatibility
Note:
This API is based on Chromium's chrome.storage API. This documentation is derived from storage.json in the Chromium code.