posthog-js
Advanced tools
Posthog-js allows you to automatically capture usage and send events to PostHog.
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.
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: 'user@example.com', 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');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 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.
For information on using this library in your app, see PostHog Docs.
This README is intended for developing the library itself.
Unit tests: run pnpm test.
Cypress: run pnpm start to have a test server running and separately pnpm cypress to launch Cypress test engine.
Testing on IE11 requires a bit more setup. TestCafe tests will use the
playground application to test the locally built array.full.js bundle. It will
also verify that the events emitted during the testing of playground are loaded
into the PostHog app. By default it uses https://us.i.posthog.com and the
project with ID 11213. See the testcafe tests to see how to override these if
needed. For PostHog internal users ask @benjackwhite or @hazzadous to invite you
to the Project. You'll need to set POSTHOG_API_KEY to your personal API key, and
POSTHOG_PROJECT_KEY to the key for the project you are using.
You'll also need to sign up to BrowserStack. Note that if you are using CodeSpaces, these variables will already be available in your shell env variables.
After all this, you'll be able to run through the below steps:
nodemon -w src/ --exec bash -c "pnpm build-rollup".export BROWSERSTACK_USERNAME=xxx BROWSERSTACK_ACCESS_KEY=xxx.npx testcafe "browserstack:ie" testcafe/e2e.spec.js.You can use the create react app setup in playground/nextjs to test posthog-js as an npm module in a Nextjs application.
posthog locally on port 8000 (DEBUG=1 TEST=1 ./bin/start).python manage.py setup_dev --no-data on posthog repo, which sets up a demo account.http://localhost:8000/project/settings and save it for the last step.cd playground/nextjs.pnpm i to install dependencies.pnpm run build-posthog-js to build posthog-js locally.NEXT_PUBLIC_POSTHOG_KEY='<your-local-api-key>' NEXT_PUBLIC_POSTHOG_HOST='http://localhost:8000' pnpm dev to start the application.Install pnpm to link a local version of posthog-js in another JS project: npm install -g pnpm
We have 2 options for linking this project to your local version: via pnpm link or via local paths
posthog-js, go to the package.json of that file, and replace the posthog-js dependency version number with file:<relative_or_absolute_path_to_local_module>package.json within posthog, replace "posthog-js": "1.131.4" with "posthog-js": "file:../posthog-js"pnpm install from the root of the project in which you just created a local pathThen, once this link has been created, any time you need to make a change to posthog-js, you can run pnpm build from the posthog-js root and the changes will appear in the other repo.
pnpm linkposthog-js directory: pnpm link --globalposthog this means: pnpm link --global posthog-js && pnpm i && pnpm copy-scripts)pnpm link --global posthog-js from within posthogJust put a bump patch/minor/major label on your PR! Once the PR is merged, a new version with the appropriate version bump will be released, and the dependency will be updated in posthog/PostHog – automatically.
If you forget to add the label, don't try to update the version locally as you won't be able to push that commit to the main branch. Instead, just make a new PR.
To release an alpha or beta version, you'll need to use the CLI locally:
Only one person is set as a collaborator on NPM, so they're the only person that can manually publish alphas
Make sure you're a collaborator on posthog-js in npm (check here).
Make sure you're logged into the npm CLI (npm login).
Check out your work-in-progress branch (do not release an alpha/beta from main).
Run the following commands, using the same bump level (major/minor/patch) as your PR:
npm version [premajor | preminor | prepatch] --preid=beta
npm publish --tag beta
git push --tags
Enjoy the new prerelease version. You can now use it locally, in a dummy app, or in the main repo.
Use the "release alpha" label on your PR to have an alpha version published automatically. This automation currently doesn't check whether an alpha exists for the version it will try to publish. If you need to publish two alphas from one PR you'll need to fix that
Remember that these versions are public and folk might use them, so make sure they're not too alpha 🙈
1.190.2 - 2024-11-27
FAQs
Posthog-js allows you to automatically capture usage and send events to PostHog.
The npm package posthog-js receives a total of 664,229 weekly downloads. As such, posthog-js popularity was classified as popular.
We found that posthog-js demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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