@philiprehberger/ts-feature-flag

Simple in-memory feature flag system with percentage rollouts and targeting.

Installation

npm install @philiprehberger/ts-feature-flag

Usage

import { createFlags } from '@philiprehberger/ts-feature-flag';

const flags = createFlags({
  newCheckout: true,
  darkMode: { percentage: 50 },
  betaFeature: { enabled: (ctx) => ctx.role === 'beta' },
});

flags.enabled('newCheckout');                     // true
flags.enabled('darkMode', { userId: 'abc' });     // deterministic by userId
flags.enabled('betaFeature', { role: 'beta' });   // true
flags.enabled('betaFeature', { role: 'user' });   // false

API

| Export | Description | |--------|-------------| | createFlags(definitions) | Create a flags instance |

Flag Types

| Type | Example | Description | |------|---------|-------------| | Boolean | true / false | Static on/off | | Percentage | { percentage: 50 } | Deterministic rollout by userId hash | | Function | { enabled: (ctx) => ... } | Custom targeting logic |

Development

npm install
npm run build
npm test

License

MIT