destr

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

Usage

Node.js

Install dependency:

# npm
npm i destr

# yarn
yarn add destr

# pnpm
pnpm i destr

Import into your Node.js project:

// ESM
import { destr, safeDestr } from "destr";

// CommonJS
const { destr, safeDestr } = require("destr");

Deno

import { destr, safeDestr } from "https://deno.land/x/destr/src/index.ts";

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

Why?

✅ Type Safe

const obj = JSON.parse("{}"); // obj type is any

const obj = destr("{}"); // obj type is unknown by default

const obj = destr<MyInterface>("{}"); // obj is well-typed

✅ Fast fallback to input if is not string

🚀 Up to 500 times faster than JSON.parse!

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

// undefined
destr();

✅ Fast lookup for known string values

🚀 Up to 900 times faster than JSON.parse!

// Uncaught SyntaxError: Unexpected token T in JSON at position 0
JSON.parse("TRUE");

// true
destr("TRUE");

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

🚀 Up to 900 times faster than JSON.parse!

// Uncaught SyntaxError: Unexpected token s in JSON at position 0
JSON.parse("salam");

// "salam"
destr("salam");

Note: This fails in safe/strict mode with safeDestr.

✅ Avoid prototype pollution

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

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

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

✅ Strict Mode

When using safeDestr it will throw an error if the input is not a valid JSON string or parsing fails. (non string values and built-ins will be still returned as-is)

// Returns "[foo"
destr("[foo");

// Throws an error
safeDestr("[foo");

Benchmarks

Locally try with pnpm benchmark. Below are results on Node.js v20.5.0 with MBA M2.

Note destr is sometimes little bit slower than JSON.parse when parsing a valid JSON string mainly because of transform to avoid prototype pollution which can lead to serious security issues if not being sanitized. In the other words, destr is better when input is not always a JSON string or from untrusted source like request body.

=== Non-string fallback ==
JSON.parse x 9,506,702 ops/sec ±1.68% (92 runs sampled)
destr x 159,565,446 ops/sec ±0.24% (98 runs sampled)
safeDestr x 73,624,106 ops/sec ±0.39% (95 runs sampled)
sjson:
@hapi/bourne x 9,404,463 ops/sec ±0.62% (96 runs sampled)
Fastest is destr

=== Known values ==
JSON.parse x 15,000,474 ops/sec ±0.82% (93 runs sampled)
destr x 96,977,026 ops/sec ±0.13% (101 runs sampled)
safeDestr x 47,618,310 ops/sec ±0.15% (98 runs sampled)
sjson x 11,176,069 ops/sec ±0.47% (93 runs sampled)
@hapi/bourne x 14,650,782 ops/sec ±0.64% (93 runs sampled)
Fastest is destr

=== plain string ==
JSON.parse (try-catch) x 11,775,641 ops/sec ±0.64% (95 runs sampled)
destr x 111,118,106 ops/sec ±0.53% (101 runs sampled)
safeDestr x 52,455,654 ops/sec ±0.21% (97 runs sampled)
sjson (try-catch) x 9,282,956 ops/sec ±0.47% (96 runs sampled)
@hapi/bourne x 11,547,144 ops/sec ±0.68% (96 runs sampled)
Fastest is destr

=== package.json ==
JSON.parse x 420,496 ops/sec ±0.20% (98 runs sampled)
destr x 358,257 ops/sec ±0.58% (98 runs sampled)
safeDestr x 351,278 ops/sec ±1.10% (98 runs sampled)
sjson x 358,003 ops/sec ±0.14% (102 runs sampled)
@hapi/bourne x 398,852 ops/sec ±0.32% (99 runs sampled)
Fastest is JSON.parse

=== broken object ==
JSON.parse (try-catch) x 137,788 ops/sec ±0.68% (98 runs sampled)
destr x 111,878 ops/sec ±0.50% (98 runs sampled)
safeDestr:
sjson (try-catch) x 219,924 ops/sec ±0.62% (98 runs sampled)
@hapi/bourne:
Fastest is sjson (try-catch)

License

MIT. Made with 💖

kricsleo / destr