Posthog Local Dev Loop

PostHog Local Dev Loop

Overview

Set up a fast, reproducible local development workflow for PostHog.

Prerequisites

• Completed posthog-install-auth setup
• Node.js 18+ with npm/pnpm
• Code editor with TypeScript support
• Git for version control

Instructions

Step 1: Create Project Structure

my-posthog-project/
├── src/
│   ├── posthog/
│   │   ├── client.ts       # PostHog client wrapper
│   │   ├── config.ts       # Configuration management
│   │   └── utils.ts        # Helper functions
│   └── index.ts
├── tests/
│   └── posthog.test.ts
├── .env.local              # Local secrets (git-ignored)
├── .env.example            # Template for team
└── package.json

Step 2: Configure Environment

# Copy environment template
cp .env.example .env.local

# Install dependencies
npm install

# Start development server
npm run dev

Step 3: Setup Hot Reload

{
  "scripts": {
    "dev": "tsx watch src/index.ts",
    "test": "vitest",
    "test:watch": "vitest --watch"
  }
}

Step 4: Configure Testing

import { describe, it, expect, vi } from 'vitest';
import { PostHogClient } from '../src/posthog/client';

describe('PostHog Client', () => {
  it('should initialize with API key', () => {
    const client = new PostHogClient({ apiKey: 'test-key' });
    expect(client).toBeDefined();
  });
});

Output

• Working development environment with hot reload
• Configured test suite with mocking
• Environment variable management
• Fast iteration cycle for PostHog development

Error Handling

Examples

Mock PostHog Responses

vi.mock('@posthog/sdk', () => ({
  PostHogClient: vi.fn().mockImplementation(() => ({
    // Mock methods here
  })),
}));

Debug Mode

# Enable verbose logging
DEBUG=POSTHOG=* npm run dev

Resources

• PostHog SDK Reference
• Vitest Documentation
• tsx Documentation

Next Steps

See posthog-sdk-patterns for production-ready code patterns.