posthog-js

What is posthog-js?

The posthog-js npm package is a JavaScript library for integrating PostHog analytics into web applications. It allows you to track user interactions, capture events, and analyze user behavior in real-time.

What are posthog-js's main functionalities?

Initialization

Initialize the PostHog library with your API key and optional configuration settings.

const posthog = require('posthog-js');
posthog.init('YOUR_API_KEY', { api_host: 'https://app.posthog.com' });

Capture Events

Capture custom events with properties to track user interactions and behaviors.

posthog.capture('event_name', { property1: 'value1', property2: 'value2' });

Identify Users

Identify users with unique IDs and associate them with properties like email and name.

posthog.identify('user_id', { email: '[e-mail]', name: 'John Doe' });

Set User Properties

Set properties for identified users to enrich user profiles with additional information.

posthog.people.set({ property1: 'value1', property2: 'value2' });

Feature Flags

Check if a feature flag is enabled for the current user to implement feature toggling.

const isEnabled = posthog.isFeatureEnabled('feature_flag_key');

Other packages similar to posthog-js

mixpanel-browser

Mixpanel is a powerful analytics tool that offers similar functionalities to PostHog, such as event tracking, user identification, and property setting. Mixpanel also provides advanced features like A/B testing and user segmentation.

amplitude-js

Amplitude is an analytics platform focused on product intelligence. It offers event tracking, user identification, and behavioral analytics. Amplitude provides advanced features like cohort analysis and user journey mapping, which can be more detailed than PostHog's offerings.

README

PostHog.js

Please see the main PostHog docs.

Specifically, the JS integration details.

Testing

Run yarn test

Releasing a new version

To release a new version, make sure you're logged in to NPM (npm login)

We tend to follow the following steps:

1. Merge your changes into master
2. Release changes as a beta version
   • npm version 1.x.x-beta.0
   • npm publish --tag beta
   • git push --tags
3. Create a PR linking to this version in the main repo
4. Once deployed and tested, write up CHANGELOG.md, and commit.
5. Release a new version
   • npm version 1.x.x
   • npm publish
   • git push --tags
6. Create a PR linking to this version in the main repo

Changelog

1.7.0 - 2020-11-26

• Send session recording events to posthog in (short) batches, separate from rest of events to make sure we drop fewer events (#126)
• Send session recording events to a separate endpoint for newer versions of posthog (#118)
• Send correct LIB_VERSION to posthog with captures (#119)
• Handle capturing self-referential objects (#123)
• Make the library smaller by dropping unneeded code (#123, #128)
• Update request batching logic (#118, #126)
• Notify rrweb when $pageview events happen (#127)
• Fix 'this.people.delete_user is undefined' (issue #39, #113)
• Update rrweb block class to use ph-no-capture and ph-ignore-input (#112)
• Deprecate calling posthog.capture with a callback (#129)
• Attempted to re-add support for including posthog-js in server-side rendering. (#131)
• Bugfix: Don't truncate session recording data (#121)
• Bugfix: Kill posthog.capture_links() and posthog.capture_forms(). They were broken since initial release - you can use autocapture instead. (#128)