React SDK

import { NexusProvider, useConfig, useFlag } from '@westyx-nexus/sdk-react';

export function App() {
  return (
    <NexusProvider
      config={{ baseUrl: 'https://blue-ocean-a5rx7.westyx.dev', apiKey: 'wxp_...' }}
      loadingFallback={<Spinner />}
    >
      <Checkout />
    </NexusProvider>
  );
}

function Checkout() {
  const showNewCheckout = useFlag('checkout.v2');
  const apiUrl = useConfig<string>('api.url');
  return showNewCheckout ? <CheckoutV2 endpoint={apiUrl} /> : <CheckoutV1 />;
}

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Latest release

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What’s new in v0.16.0

• Breaking: getSecret() removed, along with NexusPublicKeyError and NexusSecretNotFoundError. This SDK only ever holds a public key, and the backend never sends a secret to one, so the method could only ever throw. No change needed unless your code called it.

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What’s new in v0.15.0

• A live stream that never connects is reported. When the client gives up before its first successful connection it says so once - through the logger you configured, or on console.warn if you configured none. Reads keep succeeding on the TTL in that state, so without this a component looks healthy and its values simply stop changing. A connection lost after connecting is reported by useNexusStreamStatus() instead. See SSE live updates.
• The stream request carries only the API key and Accept. Both are all the server needs, which is one fewer name a deployment’s CORS configuration has to allow.

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What’s new in v0.14.0

• The package type-checks on React 18 as well as 19. Both majors the peer range admits are compiled and tested in CI, in every leg.
• An unchanged object-valued config does not re-render. A composite value’s identity is held across a sync that changed nothing.
• The API key stays out of component state. The provider’s internal configuration signature carries a digest of the key rather than the key itself.
• This package is client-only, and the documentation now says so: a server render produces loadingFallback.

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What’s new in v0.13.0

• A composite (object or array) resolution in the OpenFeature bridge carries an integer beyond Number.MAX_SAFE_INTEGER as its exact decimal string - at any depth, in objects and arrays alike, so the resolved value survives JSON.stringify. Ordinary numbers are untouched, and the scalar number resolution still answers TYPE_MISMATCH for the same value.

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What’s new in v0.12.1

• The OpenFeature provider re-fetches targeted values only when the configuration actually changed. The client reports every observable change, a stream state transition included; the provider tells the two apart through NexusClient.snapshotRevision, so a reconnect or a fall-back-to-polling costs no request and triggers no re-render.
• NexusClient.snapshotRevision - how many times the snapshot’s contents have been replaced. subscribe also fires for connection state and for the billing and quarantine flags, and this is what distinguishes a configuration change from those.
• Closing the provider releases the identity it was holding, including from a refresh that had been requested but not yet sent.
• The bridge exports NexusProviderOptions, so a caller can name the type of the options object it passes.
• The bridge requires this SDK at >=0.12.1, and its published type entry points resolve correctly from both ESM and CommonJS consumers.

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What’s new in v0.12.0

• The OpenFeature provider resolves per user. An evaluation context carrying a targetingKey selects a per-user boolean evaluation through the Nexus AB Testing add-on, so rollout percentages and cohort rules apply. The request happens on setContext, not on evaluation, so reading a flag stays synchronous; one round trip covers every flag in the snapshot. See OpenFeature.
• The provider takes options: logger and addonSuppressionMs, validated at construction.
• The provider’s resolutions were corrected: an error resolution reports DEFAULT or ERROR rather than STATIC beside the error code, an unknown flag reports FLAG_NOT_FOUND, every scalar resolution carries a variant, a number resolution no longer converts a boolean or a string into a number, and a JSON null is reported as a missing value rather than as 0.
• hasFlag(key) and getFlagKeys() on the client - whether the service defines a flag at all, and every flag key in the snapshot.

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Breaking changes

• evaluateAB() and useEvaluateAB() take string attribute values (Record<string, string>). The endpoint’s request type is string-to-string and answers anything else with a 400, so a call passing a number or a boolean was already failing; it is a compile error now.

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What’s new in v0.11.0

• Every request has a deadline. A connection a middlebox stops answering can no longer stop background refresh for the life of the page.
• A refresh is coalesced. An event burst, a TTL expiry and a manual sync arriving together produce one request, and a slow response can never be applied over a newer one.
• Unmounting releases everything - the live stream, every timer, every listener.
• Large integers survive the decode. An integer above 2^53 arrives as a bigint rather than rounded; every value a double holds exactly stays a number.
• Configuration is validated at construction, naming the option, the reason and the value.
• Status hooks track their own state. useNexusStreamStatus() and useNexusBillingOverdue() re-render when the stream or the billing state changes, not only when a sync replaces the cache.
• Built on useSyncExternalStore, so a concurrent render cannot show one flag’s old value beside another’s new one.
• Correct package resolution - import resolves ESM, require resolves CommonJS, each with matching types.
• Tested on React 18 and 19.

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Breaking changes

• A public key (wxp_) is now required; any other key is rejected at construction.
• useSecret() has been removed - a browser client holds a public key, so it could only ever return undefined.
• useNexusSyncedAt() returns epoch milliseconds rather than a Date.
• NexusLogger takes structured fields: (message, fields?), with a warn level added.
• ttlMs: 0 and an empty sseReconnectCooldown array are rejected rather than coerced into a zero delay.

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Where to start

• Installation - the registry, the token, the key
• Quick start - a working provider and your first flag
• API reference - every hook and option
• Caching behaviour - when it refreshes, and what happens when the server pushes back

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How it works

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Public keys only

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Related

• Public documentation
• All Westyx Nexus SDKs