tryjson

node tryjson ============ [![npm install][install-img]][npm-url] <br> [![Build Status][travis-img]][travis-url] [![Dependencies Status][david-img]][david-url] [![Known Vulnerabilities][snyk-img]][snyk-url] [![Downloads][downloads-img]][stats-url] [![License][license-img]][license-url] [npm-url]: https://www.npmjs.com/package/tryjson [github-url]: https://github.com/rsp/node-tryjson [readme-url]: https://github.com/rsp/node-tryjson#readme [issues-url]: https://github.com/rsp/node-tryjson/issues [license-url]: https://github.com/rsp/node-tryjson/blob/master/LICENSE.md [travis-url]: https://travis-ci.org/rsp/node-tryjson [travis-img]: https://travis-ci.org/rsp/node-tryjson.svg?branch=master [snyk-url]: https://snyk.io/test/github/rsp/node-tryjson [snyk-img]: https://snyk.io/test/github/rsp/node-tryjson/badge.svg [david-url]: https://david-dm.org/rsp/node-tryjson [david-img]: https://david-dm.org/rsp/node-tryjson/status.svg [install-img]: https://nodei.co/npm/tryjson.png?compact=true [downloads-img]: https://img.shields.io/npm/dt/tryjson.svg [license-img]: https://img.shields.io/npm/l/tryjson.svg [stats-url]: http://npm-stat.com/charts.html?package=tryjson [github-follow-url]: https://github.com/rsp [github-follow-img]: https://img.shields.io/github/followers/rsp.svg?style=social&label=Follow [twitter-follow-url]: https://twitter.com/intent/follow?screen_name=pocztarski [twitter-follow-img]: https://img.shields.io/twitter/follow/pocztarski.svg?style=social&label=Follow [stackoverflow-url]: https://stackoverflow.com/users/613198/rsp [stackexchange-url]: https://stackexchange.com/users/303952/rsp [stackexchange-img]: https://stackexchange.com/users/flair/303952.png TL;DR ----- ### JSON.parse / JSON.stringify ```js // this can crash your program // you need try/catch: object = JSON.parse(string); // this can crash your program // you need try/catch: string = JSON.stringify(object); ``` ### tryjson.parse / tryjson.stringify ```js // no need for try/catch: string = tryjson.stringify(object); // no need for try/catch: object = tryjson.parse(string); ``` Why --- Not everyone knows that you should **always** run `JSON.parse` inside of a `try/catch` block or otherwise you risk your application crashing on bad input. Most of the examples of using `JSON.parse` posted 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: ```js object = JSON.parse(string); ``` when they mean: ```js try { object = JSON.parse(string); } catch (e) { object = undefined; } ``` and now they can write it as: ```js object = tryjson.parse(string); ``` or even as: ```js object = JSON.parse(string); ``` if you want to locally override `JSON` with: ```js var JSON = require('tryjson'); ``` You can even get a different value than the default `undefined` for invalid JSON: ```js object = JSON.parse(string, {error: 'Invalid JSON'}); ``` 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 (or some other fallback value if provided). 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"` (or a JSON representation of some other fallback value if provided) - 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. Methods ------- ### `parse(string)` Returns the result of parsing `string` as JSON or `undefined` if it cannot be parsed. ### `parse(string, fallback)` Returns the result of parsing `string` as JSON or the value of `fallback` if it cannot be parsed. ### `stringify(value)` Returns the JSON representation of `value` or the JSON representation of `null` if `value` cannot be represented as JSON (e.g. contains circular references). ### `stringify(value, fallback)` Returns the JSON representation of `value` or the JSON representation of `fallback` if `value` cannot be represented as JSON (or the JSON representation of `null` if `fallback` cannot be represented as JSON as well). Rationale --------- Why `tryjson.parse` returns `undefined` for invalid JSON by default? 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. You can specify a custom fallback value as a second argument. Why `tryjson.stringify` returns `"null"` for objects that cannot be serialized by default? 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 originally equal to `null` as well. You can specify a custom fallback value as a second argument - it will be stringified to JSON if possible, or the string `"null"` will be returned. It always returns a valid JSON string. Installation ------------ Install to use in your Node project, updating the dependencies in package.json: ```sh npm install tryjson --save ``` Examples -------- Basic usage: ### Parsing ```js var tryjson = require('tryjson'); tryjson.parse('{"a":1,"b":2}'); // returns object: { a: 1, b: 2 } tryjson.parse('{"a":1,"b":2'); // returns value: undefined ``` ### Stringification ```js var tryjson = require('tryjson'); var x = {a: 1}; tryjson.stringify(x); // returns string: '{"a":1}' x.b = x; tryjson.stringify(x); // returns string: 'null' ``` ### Testing returned values ```js 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" } ``` ### Custom fallback values: ```js tryjson.parse('{"a":1,"b":2}', {err: 'bad json'}); // returns object: { a: 1, b: 2 } tryjson.parse('{"a":1,"b":2', {err: 'bad json'}); // returns object: { err: 'bad json' } var x = {a: 1}; tryjson.stringify(x, {err: 'bad object'}); // returns string: '{"a":1}' x.b = x; tryjson.stringify(x, {err: 'bad object'}); // returns string: '{"err":"bad object"}' // invalid object and invalid fallback: tryjson.stringify(x, x); // returns string: 'null' ``` Issues ------ For any bug reports or feature requests please [post an issue on GitHub](https://github.com/rsp/node-tryjson/issues). Author ------ Rafał Pocztarski - [https://github.com/rsp](https://github.com/rsp) License ------- MIT License (Expat). See [LICENSE.md](LICENSE.md) for details.