Allow persistent storage of LaunchDarkly flags so that they can be restored at startup

[ehsan]

Is your feature request related to a problem? Please describe.
We are using LD for features which should "stay" the correct value throughout the lifetime of the program, including early startup before LD has had a chance to initialize and fetch its flags. Right now we're building a custom solution in the native SDK but the JS SDK doesn't provide the necessary APIs unfortunately.

It would be nice to be able to rely on LD flags no matter when they are queried.

Describe the solution you'd like
Something similar to the solution in the .NET SDK would be great!

Describe alternatives you've considered
We haven't yet found a good alternative solution yet.

Additional context
Please see this issue and the relevant discussion there.

[eli-darkly]

To be clear, are you talking about our server-side Node SDK (this project here), or the client-side Node SDK (https://github.com/launchdarkly/node-client-sdk)? The link you provided to the .NET SDK is the client-side one. The server-side Node SDK— like most of the LaunchDarkly server-side SDKs for other languages— has several database integrations available for persistent storage.

[ehsan]

Sorry you're right, I had the wrong SDK. Apologies for the noise. 😄

[eli-darkly]

@ehsan No worries, it's a common mistake and I'm the one who would be answering your question anyway - just wanted to make sure I understood the question. It's a reasonable request, and we've had something like that in mind for a while as part of a bigger redesign of the SDK; it would probably end up looking more or less like it does in the client-side .NET SDK. One issue that's slightly different is that .NET already has a standard API for per-application/per-user file storage, with a specific convention for where the files live, and I don't think Node really provides such a thing so we would have to make some decisions about the behavior.