llmatch-js

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