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.
destr
A faster, secure and convenient alternative for JSON.parse
:
Usage
Node.js
Install using npm or yarn:
npm i destr
yarn add destr
Import into your Node.js project:
const destr = require('destr')
import destr from 'destr'
Deno
import destr from 'https://deno.land/x/destr/src/index.ts'
console.log(destr('{ "deno": "yay" }'))
Why?
Fast fallback to input if is not string:
JSON.parse()
destr()
Fast lookup for known string values:
JSON.parse('TRUE')
destr('TRUE')
Fallback to original value if parse fails (empty or any plain string):
JSON.parse('salam')
destr('salam')
Avoid prototype pollution:
const input = '{ "user": { "__proto__": { "isAdmin": true } } }'
JSON.parse(input)
destr(input)
Strict Mode
If { strict: true }
passed as second argument, destr
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)
destr('[foo')
destr('[foo', { strict: true })
Benchmarks
Locally try with pnpm benchmark
. Below are esults on Node.js 18.11.0 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 10,323,718 ops/sec ±0.45% (96 runs sampled)
destr x 1,057,268,114 ops/sec ±1.71% (90 runs sampled)
destr (strict) x 977,215,995 ops/sec ±1.43% (97 runs sampled)
sjson:
@hapi/bourne x 10,151,985 ops/sec ±0.76% (96 runs sampled)
Fastest is destr
=== Known values ==
JSON.parse x 16,359,358 ops/sec ±0.90% (92 runs sampled)
destr x 107,849,085 ops/sec ±0.34% (97 runs sampled)
destr (strict) x 107,891,427 ops/sec ±0.34% (99 runs sampled)
sjson x 14,216,957 ops/sec ±0.98% (89 runs sampled)
@hapi/bourne x 15,209,152 ops/sec ±1.08% (88 runs sampled)
Fastest is destr (strict),destr
=== Plain string ==
JSON.parse (try-catch) x 211,560 ops/sec ±0.84% (92 runs sampled)
destr x 60,315,113 ops/sec ±0.46% (98 runs sampled)
destr (strict):
sjson (try-catch) x 186,492 ops/sec ±0.70% (97 runs sampled)
@hapi/bourne:
Fastest is destr
=== standard object ==
JSON.parse x 492,180 ops/sec ±0.98% (98 runs sampled)
destr x 356,819 ops/sec ±0.40% (98 runs sampled)
destr (strict) x 412,955 ops/sec ±0.88% (94 runs sampled)
sjson x 437,376 ops/sec ±0.42% (102 runs sampled)
@hapi/bourne x 457,020 ops/sec ±0.81% (99 runs sampled)
Fastest is JSON.parse
=== invalid syntax ==
JSON.parse (try-catch) x 493,739 ops/sec ±0.51% (98 runs sampled)
destr x 405,848 ops/sec ±0.56% (100 runs sampled)
destr (strict) x 409,514 ops/sec ±0.57% (101 runs sampled)
sjson (try-catch) x 435,406 ops/sec ±0.41% (100 runs sampled)
@hapi/bourne x 467,163 ops/sec ±0.42% (99 runs sampled)
Fastest is JSON.parse (try-catch)
License
MIT. Made with 💖