parseJsonOutput

Extracts and parses JSON from LLM output, handling common formatting artifacts like markdown code fences and surrounding prose.

Import

import { parseJsonOutput } from "flowneer/plugins/output";

Usage

// Raw JSON
const data = parseJsonOutput<{ name: string }>('{"name": "Alice"}');
// → { name: "Alice" }

// Markdown-fenced JSON
const data2 = parseJsonOutput(
  'Sure! Here is the data:\n```json\n{"score": 8}\n```',
);
// → { score: 8 }

// JSON embedded in prose
const data3 = parseJsonOutput(
  'The result is {"status": "ok", "value": 42} as requested.',
);
// → { status: "ok", value: 42 }

// With a Zod validator
import { z } from "zod";
const schema = z.object({ score: z.number(), label: z.string() });
const validated = parseJsonOutput(llmOutput, schema);
// → type-safe: { score: number, label: string }

Signature

function parseJsonOutput<T = unknown>(
  text: string,
  validator?: Validator<T>,
): T;

Extraction Strategy

1. Direct parse — tries JSON.parse(text) first.
2. Code fence stripping — if that fails, looks for ```json ... ``` or ``` ... ``` blocks.
3. Embedded JSON extraction — finds the first { or [ and last matching } or ], then parses what's between them.
4. Throws parseJsonOutput: could not extract valid JSON from input if all strategies fail.

With withStructuredOutput

import { withStructuredOutput } from "flowneer/plugins/llm";
import { parseJsonOutput } from "flowneer/plugins/output";

.withStructuredOutput(MySchema, {
  parse: (raw) => parseJsonOutput(raw),  // use the robust extractor as the parse fn
})