langfuse-js's Introduction

langfuse-js

Modular mono repo for the Langfuse JS/TS client libraries.

Packages

Important

The SDK was rewritten in v2 and released on December 18, 2023. Refer to the v2 migration guide for instructions on updating your code.

Package	NPM	Environments
langfuse		Node >= 18, Web, Edge
langfuse-node		Node < 18
langfuse-langchain		Node >= 20, Web, Edge

Documentation

→ docs.langfuse.com

Development

This repository is broken into different packages

/langfuse-core > All common code goes here.
/langfuse-node > Node.js specific code
/langfuse > Web/Edge/modern Node.js specific code, using fetch and browser APIs
/langfuse-langchain > Langchain integration via callback handler

Installing dependencies

yarn

Running tests

yarn test

Integration test

Setup

Start local langfuse server
Create testing project
Set environment: LF_HOST, LF_PUBLIC_KEY, LF_SECRET_KEY

Run

# Build SDKs
yarn build

# Run E2E test
yarn test:integration

Publishing a new version

git clean -fdx -e node_modules -e .env
yarn
yarn build

Run npx lerna publish --force-publish --no-private

Bumps version number of langfuse and langfuse-node, ignores langfuse-core
Publishes to NPM, publishes also when there are no changes to keep the version numbers in sync
Confirm with npmjs OTP

Alpha: npx lerna publish prerelease --force-publish --no-private --dist-tag alpha --preid alpha

Write release notes in GitHub releases.

License

MIT

Credits

Thanks to the PostHog team for the awesome work on posthog-js-lite. This project is based on it as it was the best starting point to build a modular SDK repo to support various environments.

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