__anon_id purpose

[Siot]

Hi @DavidWells and thank you for this project.

We are currently integrating this tool in a project. But to acomplish legal requirements (RGPD) we need to explain, and offer opt-in/out, any data stored in the browser. Then,

whats the purpose of __anon_id stored in localStorage?
why is setted once Analytics is initialized? (even with all plugins disabled)

We have used a plain basic config:

{ app: 'gestio-emocional', debug: false, plugins: { // google-analytics... // google-analytics-v3... }, }

Our first strike is to initialize Analytics ASAP and enable plugins after user consent, but maybe we have to delay Analytics initialization after user consent.

Thank you.

[dobesv]

It's a good question, I'm not sure if any of the plugins make use of this currently. In our app we have our own custom analytics backend so that __anon_id acts as a session identifier we can use to track a user's activity prior to login. If they do login later we can link the activity from that anonymous ID to that user assuming it was them all along.

My guess is that it was replicated over from the segmentio analytics library that this is based on but it's potential has not yet been realized.

You can disable the use of localStorage by the library by passing storage: null as an option to the analytics constructor if I'm not mistaken. If you don't need the __anon_id or want to use analytics.storage to store persistent data that should do the trick.

Also I'm trying to propose something more smart & useful here:
#346