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Enables extensions to store and retrieve data, and listen for changes to stored items.

The storage system is based on the Web Storage API, with a few differences.

To use this API you need to include the "storage" permission in your manifest.json file. Each extension has its own storage area, which can be split into different types of storage.

Although this API is similar to Window.localStorage it is recommended that you don't use Window.localStorage in the extension code. Firefox will clear data stored by extensions using the localStorage API in various scenarios where users clear their browsing history and data for privacy reasons, while data saved using the storage.local API will be correctly persisted in these scenarios.

Types

storage.StorageArea
An object representing a storage area.
storage.StorageChange
An object representing a change to a storage area.

Properties

storage has three properties, which represent the different types of available storage area.

storage.sync
Represents the sync storage area. Items in sync storage are synced by the browser, and are available across all instances of that browser that the user is logged into, across different devices.
storage.local
Represents the local storage area. Items in local storage are local to the machine the extension was installed on.
storage.managed
Represents the managed storage area. Items in managed storage are set by the domain administrator and are read-only for the extension. Trying to modify this namespace results in an error.

Events

storage.onChanged
Fired when one or more items change in a storage area.

Browser compatibility

ChromeEdgeFirefoxFirefox for AndroidOpera
StorageAreaYesYes4548Yes
StorageChangeYesYes4548Yes
localYesYes45 *48Yes
managedYesNoNoNoNo
onChangedYesYes4548Yes
syncYes1553NoNo

Edge incompatibilities

Promises are not supported in Edge. Use callbacks instead.

Chrome incompatibilities

None.

Example extensions

Acknowledgements

This API is based on Chromium's chrome.storage API. This documentation is derived from storage.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.

Document Tags and Contributors

 Contributors to this page: andrewtruongmoz, wbamberg, abbycar, chrisdavidmills
 Last updated by: andrewtruongmoz,