A JavaScript feature flag SDK should make the safe path easy. Server-side code should evaluate a flag, pass user context, and define what happens if the evaluation cannot complete.
For Node.js services, that usually means one client per process, API keys stored outside source control, and explicit defaults at every decision point.
Install and initialize once
Initialize the client near your service startup code and reuse it for requests. Keep the API key in your server environment or secret manager.
import { ReleaseAnchor } from "@release-anchor/js";
const flags = new ReleaseAnchor({
apiKey: process.env.RELEASE_ANCHOR_KEY,
});Evaluate with context
Send a stable user identifier and the attributes your targeting rules need. Keep the fallback value explicit so the service behavior is predictable.
const useNewCheckout = await flags.evaluate("new-checkout", {
userIdentifier: user.id,
attributes: {
plan: user.plan,
country: user.country,
},
defaultValue: false,
});Keep browser and server keys separate
Do not expose server evaluation keys in client-side bundles. Evaluate sensitive flags on the server, then pass only the result to the browser when needed.
Add observability around decisions
- Log evaluation failures without logging raw API keys.
- Track which feature path served the request.
- Use Smart Insights or product metrics before expanding rollout.
Related docs
Try ReleaseAnchor
Create a flag, connect an SDK, and ship your next rollout with a safe default.