LoopKit JavaScript SDK

A complete analytics SDK for tracking events, user identification, and behavioral analytics in web applications. Now built with TypeScript for better developer experience and type safety.

Features

• 🔧 TypeScript Support: Full TypeScript support with comprehensive type definitions
• 📊 Event Tracking: Track custom events with properties
• 👤 User Identification: Identify users and track their journey
• 👥 Group Analytics: Associate users with organizations/groups
• 🔄 Zero-Config Auto Tracking: Automatic page views, clicks, and error tracking (enabled by default)
• 💾 Local Storage: Persist events offline with automatic retry
• 🌐 Cross-Platform: Works in browsers, Node.js, and React applications
• 📦 Multiple Formats: ES modules, CommonJS, UMD builds available

📖 Complete Documentation

🔗 View the complete JavaScript SDK documentation →

Installation

npm install @loopkit/javascript

CDN

<script src="https://cdn.loopkit.ai/js/loopkit.min.js"></script>

Quick Start

Browser

import LoopKit from '@loopkit/javascript';

// Initialize - auto tracking starts immediately!
LoopKit.init('your-api-key-here');
// ✅ automatically tracking page views, clicks, and errors

// Track custom events manually
LoopKit.track('button_clicked', {
  button_name: 'signup',
  page: '/homepage',
});

// Identify a user
LoopKit.identify('user_123', {
  email: '[email protected]',
  plan: 'pro',
});

Node.js

const LoopKit = require('@loopkit/javascript');

// Initialize with configuration
LoopKit.init('your-api-key-here', {
  debug: true,
  batchSize: 50,
  flushInterval: 30,
});

// Track server-side events
LoopKit.track('user_signup', {
  method: 'email',
  source: 'landing_page',
});

Auto Tracking Features (Enabled by Default)

LoopKit automatically tracks common user interactions and events out of the box. All auto tracking features are enabled by default for zero-configuration setup:

📋 Quick Reference

| Feature | Default | Event Type | Description | | ------------------------- | --------- | ------------------------------ | -------------------------------- | | enableAutoCapture | ✅ true | page_view | Page loads and navigation | | enableAutoClickTracking | ✅ true | click | Button, link, and element clicks | | enableErrorTracking | ✅ true | error | JavaScript errors and exceptions | | enableSessionTracking | ✅ true | session_start, session_end | User session lifecycle tracking |

📊 Page View Tracking (enableAutoCapture: true)

• What it tracks: Automatically captures page views on initial load and navigation
• Events generated: page_view events with URL, path, title, and referrer
• When it triggers:
  • Initial page load
  • Browser navigation (back/forward buttons)
  • Single Page App (SPA) route changes
• Event properties: url, path, search, title, referrer

🖱️ Click Tracking (enableAutoClickTracking: true)

• What it tracks: Automatically captures clicks on interactive elements
• Events generated: click events with element details and page context
• Elements tracked: Buttons, links, form inputs, and clickable elements
• Event properties: element_type, element_text, element_id, element_class, element_tag, element_href, page, page_title, page_url, position

🚨 Error Tracking (enableErrorTracking: true)

• What it tracks: Automatically captures JavaScript errors and exceptions
• Events generated: error events with error details and stack traces
• Error types: Runtime errors, syntax errors, and unhandled promise rejections
• Event properties: message, filename, lineno, colno, stack, timestamp

🔄 Session Tracking (enableSessionTracking: true)

• What it tracks: Automatically captures user session lifecycle events
• Events generated: session_start and session_end events with session metadata
• When it triggers:
  • session_start: When SDK initializes, after session timeout, or after reset
  • session_end: Before session timeout, when SDK is reset, or on page unload
• Session timeout: 30 minutes of inactivity (configurable via sessionTimeout)
• Event properties:
  • session_start: sessionId, previousSessionId (if continuing from another session)
  • session_end: sessionId, duration (in seconds), reason (timeout, reset, unload)

Zero-Config Example

// Just initialize with your API key - auto tracking starts immediately!
LoopKit.init('your-api-key');

// The SDK will now automatically track:
// ✅ Page views when users navigate
// ✅ Clicks on buttons, links, etc.
// ✅ JavaScript errors that occur
// ✅ Session start/end events
// ✅ Session management

Customizing Auto Tracking

You can disable specific auto tracking features if needed:

LoopKit.init('your-api-key', {
  enableAutoCapture: false, // Disable page view tracking
  enableAutoClickTracking: false, // Disable click tracking
  enableErrorTracking: false, // Disable error tracking
  enableSessionTracking: false, // Disable session tracking
  sessionTimeout: 60 * 60, // Custom session timeout (1 hour, in seconds)
});

TypeScript Support

The SDK is built with TypeScript and exports comprehensive type definitions:

Core Types

import type {
  // Configuration
  LoopKitConfig,
  LogLevel,
  RetryBackoff,

  // Events
  TrackEvent,
  IdentifyEvent,
  GroupEvent,
  ClickEventProperties,
  BatchEventInput,
  TrackOptions,

  // Interfaces
  ILoopKit,
  IStorageManager,
  ISessionManager,
  IQueueManager,
  INetworkManager,

  // Convenience aliases
  Config,
  Event,
  Options,
} from '@loopkit/javascript';

Configuration Types

const config: LoopKitConfig = {
  apiKey: 'your-key',
  baseURL: 'https://api.example.com',
  batchSize: 50,
  flushInterval: 30,
  debug: true,
  logLevel: 'info',

  // Auto tracking (all enabled by default)
  enableAutoCapture: true, // Page view tracking
  enableAutoClickTracking: true, // Click tracking
  enableErrorTracking: true, // Error tracking
  enableSessionTracking: true, // Auto session tracking
  sessionTimeout: 30 * 60, // Session timeout in seconds (30 minutes)

  respectDoNotTrack: true,
  onBeforeTrack: (event) => {
    // Modify event before tracking
    return { ...event, timestamp: new Date().toISOString() };
  },
  onAfterTrack: (event, success) => {
    if (!success) {
      console.warn('Failed to track event:', event);
    }
  },
  onError: (error) => {
    console.error('LoopKit error:', error);
  },
};

API Reference

API Endpoints

The SDK sends events to separate, dedicated endpoints:

• Track Events: POST /tracks with payload { tracks: [...] }
• User Identification: POST /identifies with payload { identifies: [...] }
• Group Association: POST /groups with payload { groups: [...] }

Each endpoint receives an array of the respective event type wrapped in a named property. This allows for better API performance and easier backend processing.

Initialization

LoopKit.init(apiKey, config?)

Initialize the SDK with your API key and optional configuration.

LoopKit.init('your-api-key', {
  debug: false,
  batchSize: 50,
  flushInterval: 30,

  // Auto tracking features (enabled by default - shown here for reference)
  enableAutoCapture: true, // Auto page view tracking
  enableAutoClickTracking: true, // Auto click tracking
  enableErrorTracking: true, // Auto error tracking
  enableSessionTracking: true, // Auto session tracking
  sessionTimeout: 30 * 60, // Session timeout in seconds (30 minutes)

  respectDoNotTrack: true,
  onBeforeTrack: (event) => {
    // Modify event before tracking
    return event;
  },
  onAfterTrack: (event, success) => {
    // Handle tracking result
    console.log(`Event ${event.name} ${success ? 'sent' : 'failed'}`);
  },
  onError: (error) => {
    // Handle errors
    console.error('LoopKit error:', error);
  },
});

Event Tracking

LoopKit.track(eventName, properties?, options?)

Track a custom event with optional properties.

LoopKit.track('purchase_completed', {
  amount: 99.99,
  currency: 'USD',
  product_id: 'pro_plan',
});

Note: Timestamps are automatically added to all events. You don't need to manually include timestamp in your properties - the SDK handles this automatically at the event level.

LoopKit.trackBatch(events)

Track multiple events in a single batch.

LoopKit.trackBatch([
  { name: 'page_view', properties: { page: '/home' } },
  { name: 'button_clicked', properties: { button: 'cta' } },
]);

User Management

LoopKit.identify(userId, properties?)

Associate events with a specific user.

LoopKit.identify('user_123', {
  email: '[email protected]',
  plan: 'enterprise',
  signup_date: '2024-01-15',
});

LoopKit.group(groupId, properties?, groupType?)

Associate the user with an organization or group.

LoopKit.group(
  'company_abc',
  {
    name: 'Acme Corp',
    plan: 'enterprise',
    employee_count: 500,
  },
  'organization'
);

Queue Management

LoopKit.flush()

Manually flush all queued events.

await LoopKit.flush();

LoopKit.getQueueSize()

Get the current number of events in the queue.

const queueSize = LoopKit.getQueueSize();
console.log(`${queueSize} events queued`);

LoopKit.reset()

Reset the SDK state (useful for logout).

LoopKit.reset();

Configuration Options

LoopKit.configure({
  // API Settings
  baseURL: 'https://api.loopkit.ai/v1',

  // Batching
  batchSize: 50, // Events per batch
  flushInterval: 30, // Seconds between flushes
  maxQueueSize: 1000, // Maximum events to queue

  // Performance
  enableCompression: true, // Gzip requests
  requestTimeout: 10000, // Request timeout (ms)

  // Debugging
  debug: false, // Enable debug logs
  logLevel: 'info', // 'error', 'warn', 'info', 'debug'

  // Auto-capture (Browser only) - All enabled by default for zero-config setup
  enableAutoCapture: true, // Auto-track page views
  enableAutoClickTracking: true, // Auto-track click events
  enableErrorTracking: true, // Auto-track JS errors
  enableSessionTracking: true, // Auto-track session start/end
  sessionTimeout: 30 * 60, // Session timeout in seconds (30 minutes)

  // Privacy
  respectDoNotTrack: true, // Honor DNT header
  enableLocalStorage: true, // Use localStorage for persistence

  // Retry Logic
  maxRetries: 3, // Number of retry attempts
  retryBackoff: 'exponential', // 'exponential' or 'linear'

  // Callbacks
  onBeforeTrack: (event) => {
    // Modify event before tracking
    return event;
  },
  onAfterTrack: (event, success) => {
    // Handle tracking result
    console.log(`Event ${event.name} ${success ? 'sent' : 'failed'}`);
  },
  onError: (error) => {
    // Handle errors
    console.error('LoopKit error:', error);
  },
});

Development

Building

# Install dependencies
npm install

# Build the SDK
npm run build

# Build and watch for changes
npm run build:watch

Testing

# Run tests
npm test

# Run tests in watch mode
npm run test:watch

Linting

# Lint code
npm run lint

# Format code
npm run format

Deploying

# 1. Increment version in package.json

# 2. Deploy to CDN
yarn deploy:cdn

# 3. Publish to NPM
npm publish --access public

License

MIT License. See LICENSE for details.