ensureJSON

Turn "almost-JSON" into real json. Don't worry about JSON handling. Get ensured JSON or an exception.

TL;DR

• Mission: Deliver a <3 kB, dependency‑free helper that repairs "almost‑JSON" text from LLMs and returns a valid JavaScript object—or throws JsonFixError so callers can re‑prompt.
• Scope: Sync + async API, optional Zod schema validation, minimal CLI, zero coupling to any AI vendor.
• Outcome: Published on npm as @ai/json-fix, ESM‑first with CJS fallback.

Why?

1. Broken JSON is everywhere. LLMs often miss quotes, add trailing commas, or wrap payloads in markdown fences.
2. Developers hand‑roll hacks. Teams burn time writing brittle regexes or re‑prompting, incurring latency and cost.
3. A tiny, polished utility removes that friction and quietly powers chatbots, pipelines, and edge functions—just like chalk powers terminal color.

Install

pnpm add ensureJSON
# or
npm install ensureJSON

Usage

Programmatic

import { ensureJson, JsonFixError } from "ensureJSON";

try {
  const obj = ensureJson(`{ name: "Alice", age: 42, }`);
  // obj: { name: "Alice", age: 42 }
} catch (err) {
  if (err instanceof JsonFixError) {
    // handle error, maybe re-prompt LLM
  }
}

With Zod Schema

import { ensureJson } from "ensureJSON";
import { z } from "zod";

const schema = z.object({ name: z.string(), age: z.number() });
const obj = ensureJson(`{ name: "Alice", age: 42 }`, schema);
// obj: { name: "Alice", age: 42 }

Async

import { ensureJsonAsync } from "ensureJSON";
const obj = await ensureJsonAsync(`{ name: "Alice" }`);

CLI

echo '{ name: "Alice", age: 42, }' | json-fix
# { "name": "Alice", "age": 42 }

Show help:

json-fix --help

API

• ensureJson<T>(raw: string, schema?: ZodType<T>): T
• ensureJsonAsync<T>(raw: string, schema?: ZodType<T>): Promise<T>
• JsonFixError (includes .raw property)

Features

• Repairs and parses "almost-JSON" from LLMs (GPT, Claude, etc.)
• Works in Node, Bun, Deno, Cloudflare Workers, browsers
• Sync & async API
• Optional Zod schema validation
• Minimal CLI
• Zero dependencies, pure TypeScript

License

MIT