langchain-ai/langchainjs ? reverse-engineered prompt

Build me a TypeScript framework for creating AI-powered applications. I want it to be a flexible platform that helps developers build apps with large language models more easily.

The main idea is to provide a set of standard, interoperable components for things like models, data sources, and other tools. Developers should be able to "chain" these building blocks together to create complex applications without starting from scratch. It should have a huge library of integrations so you can connect to different AI models and external systems.

Make sure it's written in TypeScript and can run in lots of different environments, like in a Node.js backend, directly in a web browser, and on modern serverless platforms like Vercel or Cloudflare Workers. It should be the JavaScript/TypeScript equivalent of the popular LangChain framework.