Package Exports

llmatch-js
llmatch-js/index.js

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Readme

llmatch-js

A JavaScript library for invoking LLMs and matching their responses with patterns. This is a JavaScript port of the Python llmatch package.

Installation

npm install llmatch-js

Features

Pattern-matching on LLM responses using regular expressions
Automatic retries with exponential backoff
Support for any LLM client with a compatible interface
Detailed verbose logging option

Usage

Basic Example

const { llmatch } = require('llmatch-js');
import { ChatLLM7 } from "langchain-llm7";

// Initialize your LLM client
const chat = new ChatLLM7()

// Create a wrapper for the LLM that matches the expected interface
const llm = {
  invoke: async (messages, options = {}) => {
    const response = await chat.invoke({
      messages: messages,
      ...options
    });
    
    return {
      content: response.content,
      raw: response
    };
  }
};

// Use llmatch to extract structured data
async function extractJson() {
  const result = await llmatch({
    llm,
    query: "Generate a JSON object with information about a random book.",
    pattern: /```json\n([\s\S]*?)```/,
    verbose: true
  });
  
  if (result.success) {
    // Parse the extracted JSON
    const bookData = JSON.parse(result.extractedData[0]);
    console.log("Book data:", bookData);
  } else {
    console.error("Failed to extract JSON:", result.errorMessage);
  }
}

extractJson().catch(console.error);

API Reference

llmatch(options)

Main function that invokes an LLM and matches the response against a pattern.

Parameter	Type	Default	Description
`llm`	Object	null	An already initialized instance of the LLM client
`query`	string	"Extract relevant data."	The main query or instruction for the LLM
`pattern`	string \| RegExp	/`(.*?)`/s	A regex string or compiled RegExp object
`context`	string	null	Optional additional text to provide context to the LLM
`promptTemplate`	string	"{query}\n\n{context}\nWrite the answer in the next format: {format}"	Template string
`maxRetries`	number	15	Maximum number of attempts to make
`initialDelay`	number	1.0	Seconds to wait before the first retry
`backoffFactor`	number	1.5	Multiplier for the delay between retries
`verbose`	boolean	false	If true, prints detailed logs of the process
`passThrough`	Object	{}	Additional parameters to pass to the LLM invocation

Return Value

The function returns a Promise that resolves to an object with the following properties:

Property	Type	Description
`success`	boolean	True if a valid response was found
`extractedData`	Array \| null	Array of strings matching the pattern (capturing groups), or null if no pattern was provided or matched
`finalContent`	string \| null	The content of the last successful or final failed LLM response
`retriesAttempted`	number	Number of retries made (0 means success on first try)
`errorMessage`	string \| null	Description of the error if success is false
`rawResponse`	any	The raw response object from the last LLM call

LLM Interface Requirements

Your LLM client should implement the following interface:

interface LLMClient {
  invoke(messages: Array<{role: string, content: string}>, options?: any): Promise<{
    content: string;
    [key: string]: any;
  }>;
}

License

MIT