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@featureflare/sdk-js

Runtime SDK reference for Node and browser contexts.

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Product and workflow docs
Use these pages when you are wiring projects, operating flags, and reviewing rollout behavior.

@featureflare/sdk-js

Runtime SDK for Node and browser contexts. Provides deterministic flag evaluation with cache, retry, stale fallback, bootstrap, and realtime update support.

More on this: React teams should layer this through @featureflare/react unless they need direct client control.

Install

pnpm add @featureflare/sdk-js

Package page: npmjs.com/package/@featureflare/sdk-js

Primary API

  • FeatureFlareClient constructor with apiBaseUrl, sdkKey, timeout/retry, cache, bootstrap, and realtime settings.
  • bool(flagKey, user, defaultValue): fast boolean evaluation with fallback behavior.
  • evaluate(flagKey, user, defaultValue): returns value plus diagnostics metadata.
  • flags(user, defaultValue): bulk boolean map retrieval for a user context.

Minimal usage

import { FeatureFlareClient } from '@featureflare/sdk-js';

const client = new FeatureFlareClient({
  sdkKey: process.env.FEATUREFLARE_SERVER_KEY
});

const enabled = await client.bool('new-nav', { id: 'user-123' }, false);

Operational notes

  • Cache-first order: fresh cache, stale cache with revalidate, bootstrap/persistent, then default.
  • Kill-switch semantics win over positive evaluations.
  • Realtime can use SSE with polling fallback for release-safe updates.
  • Use server keys only in trusted server runtime.

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