@flagswift/node-server

Official Node.js server SDK for FlagSwift feature flags.

Installation

npm install @flagswift/node-server

Quick Start

import { FlagSwiftServer } from '@flagswift/node-server'

const flagClient = new FlagSwiftServer({
  apiKey: process.env.FLAGSWIFT_SERVER_KEY!,
  environment: 'production',
})

await flagClient.initialize()

if (flagClient.isEnabled('new-feature')) {
  // ...
}

API

new FlagSwiftServer(config)

{
  apiKey: string,              // required — server key (fs_server_...)
  environment: string,         // required
  baseUrl?: string,
  refreshInterval?: number,
  timeout?: number,
  cacheTimeout?: number,
  maxRetries?: number,
  failsafeFallbacks?: Record<string, boolean>,
  killSwitchFallbacks?: Record<string, boolean>,
  globalIdentifier?: string | string[],
}

initialize(): Promise<void>

Must be called once before using flag methods.

isEnabled(flagName: string, user?: UserContext): boolean

const isEnabled = flagClient.isEnabled('premium-feature', {
  identifier: '[email protected]',
})

evaluateFlags(flagNames: string[], user?: UserContext): Record<string, boolean>

Batch-check multiple flags in one call.

activateKillSwitch(options) / deactivateKillSwitch(options)

Emergency server-side flag shutdown. See kill switch docs.

await flagClient.activateKillSwitch({
  flags: ['risky-feature'],
  environments: ['production'],
})

checkFlag(flagName, options): Promise<boolean>

One-off flag check without a persistent client — useful for serverless functions.

Links

• Documentation
• Source

License

MIT