A/B Testing SDK

A lightweight, deterministic A/B testing SDK for React applications.

Features

• Deterministic Variant Assignment: Same user always gets the same variant
• Zero Network Latency: Instant assignment with local bucketing
• Event Tracking: Record user interactions for analytics
• TypeScript Support: Full type safety
• React Hooks: Easy-to-use React integration
• Tree-shakeable: Only import what you need

Installation

npm install hefmartest

Quick Start

Initialize the SDK

import { initABTestClient } from 'hefmartest'

initABTestClient({
  userId: 'user-123',
  apiUrl: 'http://localhost:3000/api',
  enableBackendSync: true
})

Use in React Components

import { useVariant, useTrackEvent } from 'hefmartest/react'

function MyComponent() {
  const { variant, loading } = useVariant('my-experiment')
  const trackEvent = useTrackEvent('my-experiment')

  if (loading) return <div>Loading...</div>

  return (
    <div>
      {variant?.key === 'control' ? (
        <button onClick={() => trackEvent('click')}>Original</button>
      ) : (
        <button onClick={() => trackEvent('click')}>New Design</button>
      )}
    </div>
  )
}

Core API

initABTestClient(config)

Initialize the SDK client.

Options:

• userId (required): Unique user identifier
• apiUrl (optional): Backend API URL (default: http://localhost:3000/api)
• enableBackendSync (optional): Send events to backend (default: true)

getABTestClient()

Get the initialized client instance.

const client = getABTestClient()
const variant = await client.getVariant('my-experiment')

assignVariant(experimentKey, userId, variants)

Direct variant assignment without initialization.

import { assignVariant } from 'hefmartest'

const variant = assignVariant('my-exp', 'user-123', [
  { key: 'control', weight: 50 },
  { key: 'treatment', weight: 50 }
])

React Hooks

useVariant(experimentKey)

Get variant assignment for an experiment.

const { variant, loading, error } = useVariant('my-experiment')

useTrackEvent(experimentKey)

Track events for an experiment.

const trackEvent = useTrackEvent('my-experiment')
trackEvent('click', { position: 'top' })

useUserID()

Get and set the current user ID.

const { userId, setUserId } = useUserID()

Browser Support

• Chrome (latest)
• Firefox (latest)
• Safari (latest)
• Edge (latest)

License

MIT