@flagcontrol/core

The core SDK for FlagControl - providing shared logic for feature flag evaluation, real-time streaming, and list management.

Overview

This package contains the core functionality used by all FlagControl SDKs:

• Flag evaluation - Local and remote evaluation modes
• Real-time updates - Fetch-based streaming that works in Node.js, edge runtimes, and browsers
• Incremental sync - Cursor-based change tracking for efficient updates
• List management - Create, update, and manage targeting lists

Installation

npm install @flagcontrol/core

Note: Most users should install @flagcontrol/node or @flagcontrol/react instead, which include this package and provide a more convenient API.

Usage

import { createBaseClient } from '@flagcontrol/core';

const client = createBaseClient({
  sdkKey: 'YOUR_SDK_KEY',
  evaluationMode: 'local', // or 'remote'
});

await client.waitForInitialization();

// Evaluate flags
const value = client.get('my-flag', {}, 'default-value');

// Check if enabled
const isEnabled = client.isEnabled('feature-flag', { userId: 'user-123' });

// List operations
await client.addToList('beta-users', { key: 'user-123' });
await client.removeFromList('beta-users', 'user-123');

// Manual sync
await client.syncChanges();

Related Packages

| Package | Description | |---------|-------------| | @flagcontrol/node | Node.js SDK for server-side usage | | @flagcontrol/react | React SDK with hooks and provider | | flagcontrol | CLI for TypeScript type generation |

Documentation

For full documentation, visit flagcontrol.com/docs.

License

MIT