storage

Enables WebExtensions 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 WebExtension has its own storage area, which can be split into different types of storage.

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.

	Edge	Firefox	Chrome	Opera
`StorageArea`	?	45.0	Yes	33
`StorageArea.clear`	?	45.0	Yes	33
`StorageArea.get`	?	45.0	Yes	33
`StorageArea.getBytesInUse`	?	45.0	Yes	33
`StorageArea.remove`	?	45.0	Yes	33
`StorageArea.set`	?	45.0	Yes	33
`StorageChange`	?	45.0	Yes	33
`local`	?	45.0	Yes	33
`managed`	?	No	Yes	No
`onChanged`	?	45.0	Yes	33
`sync`	?	No	Yes	No

	Firefox
`StorageArea`	48.0
`StorageArea.clear`	48.0
`StorageArea.get`	48.0
`StorageArea.getBytesInUse`	48.0
`StorageArea.remove`	48.0
`StorageArea.set`	48.0
`StorageChange`	48.0
`local`	48.0
`managed`	No
`onChanged`	48.0
`sync`	No

Chrome incompatibilities

Firefox does not support:
- managed storage area
- sync storage area
- getBytesInUse().
The storage API is not supported in content scripts.

Example add-ons

Acknowledgements

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

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