destr

What is destr?

The `destr` npm package is designed to safely parse JSON strings without throwing an error for invalid JSON. It can return the original string if parsing fails, making it useful for handling dynamic JSON data that may not always be properly formatted. It also recognizes and correctly parses values like `null`, `true`, `false`, and `undefined`.

What are destr's main functionalities?

Safe JSON parsing

Safely parse a JSON string without throwing an error. If the string is not valid JSON, it returns the original string.

"const destr = require('destr');
const json = '{\"key\":\"value\"}';
const parsed = destr(json);
console.log(parsed); // Output: { key: 'value' }"

Parsing special JSON values

Correctly parse special JSON values such as `null`, `true`, `false`, and `undefined`, returning their corresponding JavaScript types.

"const destr = require('destr');
console.log(destr('null')); // Output: null
console.log(destr('true')); // Output: true
console.log(destr('false')); // Output: false
console.log(destr('undefined')); // Output: undefined"

Other packages similar to destr

json5

Similar to `destr`, `json5` allows for parsing of JSON data with more lenient syntax rules, such as trailing commas and comments. However, `json5` focuses on extending JSON syntax to be more flexible, while `destr` focuses on safe parsing and handling special values.

safe-json-parse

This package offers functionality similar to `destr` by providing a safe way to parse JSON strings without throwing errors for invalid JSON. The main difference is in the API and specific handling of non-JSON values.

README

destr

A faster, secure and convenient alternative for JSON.parse:

Usage

Node.js

Install using npm or yarn:

npm i destr
# or
yarn add destr

Import into your Node.js project:

// CommonJS
const destr = require('destr')

// ESM
import destr from 'destr'

Deno

import destr from 'https://cdn.jsdelivr.net/gh/nuxt-contrib/destr/src/index.ts'

console.log(destr('{ "deno": "yay" }'))

Why?

⚠️ Before reading cool features, please note that destr is not always faster! When parsing a standard JSON string it is about 3 times slower mainly because of transform to avoid prototype pollution which can lead to serious security issues if not being sanetized.

In the other words, destr is better when input is not always a json string or from untrsuted source like request body.

Fast fallback to input if is not string:

// Uncaught SyntaxError: Unexpected token u in JSON at position 0
JSON.parse()

// undefined
destr()

// JSON.parse x 5,363,773 ops/sec ±0.31% (96 runs sampled)
JSON.parse(3.14159265359)

// destr x 660,537,795 ops/sec ±0.06% (86 runs sampled)
destr(3.14159265359)

Fast lookup for known string values:

// Uncaught SyntaxError: Unexpected token T in JSON at position 0
JSON.parse('TRUE')

// true
destr('TRUE')

// JSON.parse x 10,432,994 ops/sec ±0.23% (94 runs sampled)
JSON.parse('true')

// destr x 652,107,152 ops/sec ±0.11% (94 runs sampled
destr('true')

Fallback to original value if parse fails (empty or any plain string):

// Uncaught SyntaxError: Unexpected token s in JSON at position 0
// JSON.parse (try-catch) x 248,749 ops/sec ±1.66% (93 runs sampled)
JSON.parse('salam')

// destr x 32,415,523 ops/sec ±0.57% (94 runs sampled)
destr('salam')

Avoid prototype pollution:

const input = '{ "user": { "__proto__": { "isAdmin": true } } }'

// { user: { __proto__: { isAdmin: true } } }
JSON.parse(input)

// { user: {} }
destr(input)

Better types:

interface JSON {
  parse(text: string, reviver?: (this: any, key: string, value: any) => any): any
}

function destr(val: string | any): JSONValue | undefined

License

MIT. Made with 💖