L3-Chains RouterOutputParser fails in JS

Short Course Q&A LangChain for LLM Application Development
1

I’m attempting to follow the course using the LangChain JS api. In the L3 MultiPromptChain the RouterOutputParser is throwing an error attempting to parse the output, but as far as I can tell the output is correct according to the prompt. I’ve extracted the output it’s failing to parse and can recreate the error with this short snippet:

import { RouterOutputParser } from 'langchain/output_parsers';

let outputParser = new RouterOutputParser();

let result = await outputParser.parse('```json\n' +
    '{\n' +
    '    "destination": "physics",\n' +
    '    "next_inputs": "Explain black body radiation"\n' +
    '}\n' +
    '```');

Any ideas why this is failing?

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2

i encountered the same issue in the original python code.

i changed the last sentence of MULTI_PROMPT_ROUTER_TEMPLATE and it worked.

change to →

<< OUTPUT (remember to include the ```json and ```)>>"""

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