New Shared Storage features in M135: Custom data origin in createWorklet

Hey all,

We're introducing updates to the Shared Storage API in M135, enabling you to set a custom data origin in calls to createWorklet().

In M130 we added the dataOrigin property to the createWorklet() call to allow reading and writing to a shared storage data partition that is different from the invoking browsing context. dataOrigin can be set to context-origin or script-origin. As of M135 you can also set dataOrigin to be the URL of a custom data origin.

sharedStorage.createWorklet(scriptUrl,

{ dataOrigin: "https://custom-data-origin.example" });

When using a custom data origin, the data is stored in the Shared Storage of the defined origin. The script endpoint has to respond with the header Shared-Storage-Cross-Origin-Worklet-Allowed and CORS should be enabled.

Consent from the custom data origin owner is also required. The owner must host a JSON file at /.well-known/shared-storage/trusted-origins listing the scriptOrigin and contextOrigin combinations that are allowed to process their Shared Storage data. Both scriptOrigin and contextOrigin can be either a string or an array.

[{

   "scriptOrigin": "https://cdn-ad.example",

   "contextOrigin": "https://publisher.example"

}]

The Shared Storage Implementation documentation has been updated to reflect these changes and provide further guidance on using custom data origins.