storage.StorageArea.onChanged
Fires when one or more items in a storage area change. Compared to storage.onChanged
, this event enables you to listen for changes in one of the storage areas: local
, managed
, session
, and sync
.
Syntax
js
// local can also be sync, managed, or session
browser.storage.local.onChanged.addListener(listener)
browser.storage.local.onChanged.removeListener(listener)
browser.storage.local.onChanged.hasListener(listener)
Events have three functions:
addListener(listener)
-
Adds a listener to this event.
removeListener(listener)
-
Stops listening to this event. The
listener
argument is the listener to remove. hasListener(listener)
-
Checks whether
listener
is registered for this event. Returnstrue
if it is listening,false
otherwise.
addListener syntax
Parameters
listener
-
The function called when this event occurs. The function is passed this argument:
changes
-
object
. Object describing the change. This contains one property for each key that changed. The name of the property is the name of the key that changed, and its value is astorage.StorageChange
object describing the change to that item.
Examples
js
/*
Log the old value and its new value of
changes in the local storage.
*/
function logStorageChange(changes) {
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.local.onChanged.addListener(logStorageChange);
Browser compatibility
BCD tables only load in the browser
Note: This API is based on Chromium's chrome.storage
API. This documentation is derived from storage.json
in the Chromium code.