LangChain JavaScript Example

A sample Node script that uses LangChain to talk to LLMs.

You’ll need an API key for each LLM. So just follow the instructions linked below to obtain your API keys.

• OpenAI ChatGPT
• Anthropic Claude
• Google Gemini

Save the keys to the app/src/main/resources/.env file as the corresponding ..._API_KEY environment variable. You can use app/src/main/resources/.env.template as a guide to structure your .env file.

Install packages, if you haven't already.

pnpm install

To Run

The sample logic is in the file index.js.

To run against OpenAI's ChatGPT:

pnpm run main --model openai

To run against Anthropic's Claude:

pnpm run main --model anthropic

To run against Google's Gemini:

pnpm run main --model google

To run against DeekSeek's R1:

pnpm run main --model deepseek

If you don't specify --model, it will default to openai and use ChatGPT.