Version: Latest (3.0)1.1

Configure Persistent Data Storage in JavaScript SDK

While loading the JavaScript SDK, you can specify the information to store (userId, anonymousId, session information, etc.) and whether to store it in your browser or not store it at all (fully anonymous tracking).

The fully anonymous tracking feature is a part of RudderStack’s Data Governance toolkit that ensures the quality and integrity of your data in a secure and compliant manner.

Persisted data

You can use the JavaScript SDK to persist the following data:

• User (ID and traits)
• Group (ID and traits)
• Anonymous user ID
• Initial referrer and domain
• Session
• Authentication token

Set storage type

To set the storage type for your stored information, provide a type field in the storage option while loading the JavaScript SDK:

rudderanalytics.load(WRITE_KEY, DATA_PLANE_URL, {
  storage: {
    type: "cookieStorage" / "localStorage" / "sessionStorage" / "memoryStorage" / "none"
  }
  // other load options
});

The type parameter accepts the following values:

If not specified, the SDK sets the default storage type to cookieStorage and uses it to store all user data.

Set storage for specific information type

You can also set a different storage option for a specific information while loading the JavaScript SDK. Use the entries object in the storage load option and define the storage type for your user data.

Note that:

• The storage options set in the entries object override the global storage type.
• The SDK uses the global storage type for storing user data that is not explicitly defined in the entries object.
• The SDK migrates the existing user data to the newly selected storage option automatically.
• The SDK removes any stored user data if you set type to none.

rudderanalytics.load(WRITE_KEY, DATA_PLANE_URL, {
  storage: {
    entries: {
      userId: {
        type: "cookieStorage"
      },
      userTraits: {
        type: "localStorage"
      },
      sessionInfo: {
        type: "none"
      }
    }
  }
  // other load options
});

In the above snippet, the global storage type is not defined. Hence, the SDK uses cookieStorage as the default storage option. Based on the entries object configured above, the SDK stores the user information as follows:

Use cases

Suppose you define the following storage configurations for userId while loading the JavaScript SDK:

Case 1

rudderanalytics.load(WRITE_KEY, DATA_PLANE_URL, {
  storage: {
    entries: {
      userId: {
        type: "cookieStorage"
      },
    }
  }
  // other load options
});

When you trigger an identify call with user123 as the userId, the SDK persists user123 in the cookie storage. If a track call is triggered next, the payload will contain user123 as the userId.

Case 2

rudderanalytics.load(WRITE_KEY, DATA_PLANE_URL, {
  storage: {
    entries: {
      userId: {
        type: "none"
      },
    }
  }
  // other load options
});

When you trigger an identify call, the SDK will not store the userId and the next set of events will have userId as an empty string ("").

Case 3

If you set the global storage type to none and then define the type in the entries object, then the SDK will not treat it as truly anonymous tracking.

rudderanalytics.load(WRITE_KEY, DATA_PLANE_URL, {
  storage: {
    type: "none",
    entries: {
      userId: {
        type: "cookieStorage"
      },
    }
  }
  // other load options
});

In this case, the SDK replicates the behavior described in Case 1.

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