JSON Repair - TypeScript Implementation

A complete TypeScript port of the popular json-repair Python library.

This library can fix invalid JSON strings, which is especially useful when dealing with LLM outputs that may have malformed JSON.

✅ 100% Feature Parity | ✅ Fully Type-Safe | ✅ Production Ready

Features

• Fix missing quotes, brackets, and commas
• Handle incomplete arrays and objects
• Auto-complete missing values
• Remove comments from JSON
• Support for streaming/incomplete JSON
• Strict mode for validation

Installation

npm install @yarmu/json-repair

Usage

import { repairJson, loads } from '@yarmu/json-repair';

// Repair and return as string
const fixed = repairJson('{"name": "John", "age": 30');
console.log(fixed); // '{"name": "John", "age": 30}'

// Repair and parse to object
const obj = loads('{"name": "John", "age": 30');
console.log(obj); // { name: 'John', age: 30 }

API

repairJson(jsonStr, options?)

Repairs a JSON string and returns the fixed JSON string or parsed object.

Parameters:

• jsonStr (string): The JSON string to repair
• options (object, optional):
  • returnObjects (boolean): If true, return parsed object instead of string. Default: false
  • skipJsonParse (boolean): Skip initial JSON.parse validation. Default: false
  • logging (boolean): Return repair log along with result. Default: false
  • streamStable (boolean): Keep repairs stable for streaming JSON. Default: false
  • strict (boolean): Raise errors instead of repairing certain issues. Default: false

Returns: string | JSONReturnType | [JSONReturnType, RepairLog[]]

loads(jsonStr, options?)

Works like JSON.parse() but repairs the JSON first.

Parameters:

• jsonStr (string): The JSON string to parse
• options (object, optional):
  • skipJsonParse (boolean): Skip initial JSON.parse validation. Default: false
  • logging (boolean): Return repair log along with result. Default: false
  • streamStable (boolean): Keep repairs stable for streaming JSON. Default: false
  • strict (boolean): Raise errors instead of repairing. Default: false

Returns: JSONReturnType | [JSONReturnType, RepairLog[]]

load(fd, options?)

Read and repair JSON from a file descriptor.

Parameters:

• fd (number): File descriptor
• options (object, optional): Same as loads

Returns: JSONReturnType | [JSONReturnType, RepairLog[]]

fromFile(filename, options?)

Read and repair JSON from a file.

Parameters:

• filename (string): Path to JSON file
• options (object, optional): Same as loads

Returns: JSONReturnType | [JSONReturnType, RepairLog[]]

Examples

import { repairJson, loads } from '@yarmu/json-repair';

// Missing closing brace
repairJson('{"name": "John"'); // '{"name": "John"}'

// Missing quotes
repairJson('{name: "John"}'); // '{"name": "John"}'

// Trailing comma
repairJson('{"name": "John",}'); // '{"name": "John"}'

// With comments
repairJson('{"name": "John" /* comment */}'); // '{"name": "John"}'

// Direct parsing
const obj = loads('{"name": "John", "age": 30');
// Returns: { name: 'John', age: 30 }

// With logging
const [result, log] = repairJson('{"name": "John"', {
  returnObjects: true,
  logging: true
});
console.log(log); // Array of repair operations

// Strict mode (throws on structural issues)
try {
  repairJson('{"key": "value", "key": "duplicate"}', { strict: true });
} catch (e) {
  console.error('Duplicate keys found!');
}

License

MIT

Credits

This is a TypeScript port of the Python json-repair library by Stefano Baccianella.