PostHog integration for JavaScript Node

Workflow

1. basic-integration-1.0-begin.md

   - PostHog Setup - Begin ← Start here

2. basic-integration-1.1-edit.md

   - PostHog Setup - Edit

3. basic-integration-1.2-revise.md

   - PostHog Setup - Revise

4. basic-integration-1.3-conclude.md

   - PostHog Setup - Conclusion

Reference files

• references/node.md

  - Node.js - docs

• references/posthog-node.md

  - PostHog Node.js SDK

• references/identify-users.md

  - Identify users - docs

• references/basic-integration-1.0-begin.md

  - PostHog setup - begin

• references/basic-integration-1.1-edit.md

  - PostHog setup - edit

• references/basic-integration-1.2-revise.md

  - PostHog setup - revise

• references/basic-integration-1.3-conclude.md

  - PostHog setup - conclusion

Key principles

• Environment variables: Always use environment variables for PostHog keys. Never hardcode them.
• Minimal changes: Add PostHog code alongside existing integrations. Don't replace or restructure existing code.
• Match the example: Your implementation should follow the example project's patterns as closely as possible.

Framework guidelines

• posthog-node is the Node.js server-side SDK package name – do NOT use posthog-js on the server
• Include enableExceptionAutocapture: true in the PostHog constructor options
• Add posthog.capture() calls in route handlers for meaningful user actions – every route that creates, updates, or deletes data should track an event with contextual properties
• Add posthog.captureException(err, distinctId) in the application's error handler (e.g., Express error middleware, Fastify setErrorHandler, Koa app.on('error'))
• In long-running servers, the SDK batches events automatically – do NOT set flushAt or flushInterval unless you have a specific reason to
• For short-lived processes (scripts, CLIs, serverless), set flushAt to 1 and flushInterval to 0 to send events immediately
• Reverse proxy is NOT needed for server-side Node.js – only client-side JavaScript needs a proxy to avoid ad blockers
• Remember that source code is available in the node_modules directory
• Check package.json for type checking or build scripts to validate changes

Identifying users

X-POSTHOG-DISTINCT-ID

X-POSTHOG-SESSION-ID

Error tracking