Description #
LangChain.js is a JavaScript library designed for building applications powered by large language models (LLMs) with features like prompt management, memory, and chaining. It enables developers to create sophisticated AI workflows in web apps.
History #
LangChain.js is the JavaScript implementation of the popular LangChain Python framework, which emerged in 2022 to simplify building applications with LLMs. The JS version extends support to web and Node.js environments.
Hello World Code #
import { OpenAI } from "langchain/llms/openai";
const model = new OpenAI();
async function run() {
const response = await model.call("Hello, LangChain.js!");
console.log(response);
}
run();How to Run #
Option 1: Online
Test in online JS environments like Replit or local Node.js.
Option 2: Local
- Install with npm:
npm install langchain- Run scripts with Node.js.
Key Concepts #
- Simplifies working with LLMs in JavaScript
- Supports prompt templates and chains of calls
- Provides memory management for conversation context
- Integrates with OpenAI and other LLM providers
- Supports document loading and text splitting
- Enables chatbots, summarizers, and agents
- Compatible with React, Next.js, and other frameworks
- Modular and extensible architecture
- Open source with growing adoption
- Ideal for AI-powered web apps and tools
Try It Online #
Fun Facts #
- LangChain.js powers many next-gen AI chatbots and assistants.
- It abstracts complex prompt engineering into simple APIs.
- The framework supports multi-step AI workflows easily.
- LangChain.js was released soon after its Python counterpart due to demand.
- Developers use it to build context-aware and persistent LLM apps.
