node tryjson

Why

Not everyone knows that you should always run JSON.parse inside of the try/catch block or otherwise you risk your application crashing on bad input. Most of the examples of using JSON.parse that I see online never does that. People usually assume that you will get undefined on bad or empty input but you don't.

Remember: Always try { JSON.parse() } or use tryjson.parse()

This module works like many people assume that the built-in JSON works and can simplify some common code. People usually write:

object = JSON.parse(string);

when they mean:

try {
  object = JSON.parse(string);
} catch (e) {
  object = undefined;
}

and now they can write it as:

object = tryjson.parse(string);

or even as:

object = JSON.parse(string);

if you want to locally override JSON with:

var JSON = require('tryjson');

How it works

This module works like JSON.parse (and in fact it uses JSON.parse) but instead of throwing exceptions it returns undefined on failure. This is not always a desired behaviour but sometimes it is.

There is also a stringify method that works like JSON.stringify but instead of throwing exceptions on circular structures it returns "null" - which, again, may not be what you always want but sometime it is and you can use this module to simplify your code in those cases.

Rationale

Why tryjson.parse returns undefined for invalid JSON? Because a valid JSON can never be parsed to undefined so you can test it reliably for that value with value === undefined to know if it was invalid.

Why tryjson.stringify returns "null" for objects that cannot be serialized? Because "null" is a valid JSON string so it can always be parsed without errors and is still easy to test for null value. Note that this time, getting "null" does not necessarily mean that the object couldn't be serialized because it might have been null as well.

Installation

Install to use in your Node project, updating the dependencies in package.json:

npm install tryjson --save

Examples

Basic usage:

Parsing

var tryjson = require('tryjson');

console.log(tryjson.parse('{"a":1,"b":2}'));
// { a: 1, b: 2 }

console.log(tryjson.parse('{"a":1,"b":2'));
// undefined

Stringification

var tryjson = require('tryjson');

var x = {a: 1};
console.log(tryjson.stringify(x));
// '{"a":1}'
x.b = x;
console.log(tryjson.stringify(x));
// 'null'

Testing returned values

var object = tryjson.parse(string);

if (object === undefined) {
  // the string was invalid JSON
}

if (object == null) {
  // the string was either invalid JSON or "null"
}

if (!object) {
  // the string was either invalid JSON, "null", "false" or "0"
}

Issues

For any bug reports or feature requests please post an issue on GitHub.

Author

Rafał Pocztarski - https://github.com/rsp

License

MIT License (Expat). See LICENSE.md for details.