measurementId property

The unique Google-assigned identifier of the Google Analytics web stream associated with the WebApp.

Firebase SDKs use this ID to interact with Google Analytics APIs. This field is only present if the WebApp is linked to a web stream in a Google Analytics App + Web property. Learn more about this ID and Google Analytics web streams in the Analytics documentation. To generate a measurementId and link the WebApp with a Google Analytics web stream, call [AddGoogleAnalytics](../../v1beta1/projects/addGoogleAnalytics). For apps using the Firebase JavaScript SDK v7.20.0 and later, Firebase dynamically fetches the measurementId when your app initializes Analytics. Having this ID in your config object is optional, but it does serve as a fallback in the rare case that the dynamic fetch fails.