LaunchDarkly: how to access flag values from `localStorage`

Question

I'm using LaunchDarkly in a web app and am playing around with using the 'localStorage' bootstrap option on initialization.

With this option I clearly see my flags in localStorage and they look to be under a key formed with my clientId and then some long, base64 string - I'm curious if there is a clear pattern I can use to access the flag values in localStorage with getItem or if I'm perhaps completely misinterpreting the use case?

What I tried was adding the optional bootstrap option and then logging out my localStorage to see what key the flag values were being stored in, and they appear to be mapped to a key that includes my LD client ID and then some long, seemingly random string.

What I expected was for my keys to be stored under a key of maybe just my LD client ID or some other, easily found property name.

Thank you for any and all insight!

Best, Zach

have you tried decoding this *long, base64 string* - perhaps there's meaning there — Jaromanda X, Oct 31 '22 at 23:59
looks like it is the base64 encoding of `JSON.stringify(user)` where `user` is some object or other — Jaromanda X, Nov 01 '22 at 00:13

score 0 · Answer 1 · answered Feb 10 '23 at 12:45

The JavaScript client SDK already caches flags in localstorage for you. When the SDK initializes, the flag values for the context (i.e. user) you provide are pulled and cached in localStorage. From that point on, LaunchDarkly's SDK uses localStorage for getting flag values, speeding up flag evaluations and ensuring that flags can be evaluated in the circumstance where LaunchDarkly is temporarily unavailable. Updates to this localStorage cache are streamed by default (though you an configure this for polling).

My point is, there may be no need for bootstrapping off localStorage. Bootstrapping on the client-side is useful for situations where you are writing these values prior to the response hitting the client's browser (for example, you are writing bootstrapped values at the edge).

LaunchDarkly: how to access flag values from `localStorage`

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