Hello LangChain.js

Run locally

Create a .env file with the API key. Refer this example: https://github.com/langchain-ai/langchainjs/blob/main/examples/.env.example

yarn intall

npx vite-node <filename>.ts
or
yarn dev --watch <filename>.ts

https://www.deeplearning.ai/short-courses/build-llm-apps-with-langchain-js/