JavaScript SDK

The official JavaScript/TypeScript SDK for Replane. Works in Node.js 18+, browsers, Deno, and Bun.

Installation

npm install @replanejs/sdk

Quick start

import { Replane } from '@replanejs/sdk'

// Define your config types
interface Configs {
  'feature-dark-mode': boolean
  'api-rate-limit': number
  'pricing-tiers': { free: number; premium: number }
}

// Create the client
const replane = new Replane<Configs>()

// Connect to the server
await replane.connect({
  sdkKey: process.env.REPLANE_SDK_KEY,
  baseUrl: 'https://replane.example.com'
})

// Get a config value
const darkModeEnabled = replane.get('feature-dark-mode')

// Get with context for override evaluation
const rateLimit = replane.get('api-rate-limit', {
  context: { userId: user.id, plan: user.plan }
})

// Subscribe to realtime updates
replane.subscribe('feature-dark-mode', (config) => {
  console.log('Dark mode changed:', config.value)
})

// Cleanup when done
replane.disconnect()

Features

• Type safety — Full TypeScript support with generics
• Real-time updates — SSE connection for instant config changes
• Context-based overrides — Target users, plans, regions, etc.
• Zero dependencies — Pure JavaScript, works everywhere
• Resilient — Automatic reconnection and local caching

Environment compatibility

Environment	Support
Node.js 18+	Full
Node.js 16-17	Requires fetch polyfill
Browsers (modern)	Full
Deno	Full
Bun	Full
Edge Workers	Full (Cloudflare, Vercel)

Next steps

• API Reference — Full API documentation
• Guide — Configuration, testing, best practices
• Feature Flags — Toggle features
• Override Rules — Target specific users