[How-to guides](https://js.langchain.com/docs/how_to/): LLM should read this page when (needing to find specific implementation guides for LangChain.js, looking for solutions to common LLM application problems, or planning how to implement particular features in a LangChain project) (Comprehensive index of how-to guides for LangChain.js covering core functionality including installation, LCEL, components (prompts, models, retrievers, etc.), and use cases like RAG, extraction, chatbots, and SQL/graph database integration, with links to related technologies like LangGraph.js and LangSmith)

