fast-safe-stringify

What is fast-safe-stringify?

The fast-safe-stringify package is designed for safely converting JavaScript objects into JSON strings without running into issues like circular references, which can cause the native JSON.stringify to throw an error. It aims to provide a fast and safe way to serialize objects, including those that may contain circular references, functions, and other non-JSON-safe values.

What are fast-safe-stringify's main functionalities?

Safe serialization of circular references

This feature allows you to safely serialize objects that contain circular references, which would otherwise throw an error with JSON.stringify.

const stringify = require('fast-safe-stringify');
const obj = {};
obj.a = { b: obj };
console.log(stringify(obj));

Stable serialization

Provides an option for stable serialization, where the output JSON string's property order is deterministic, making it suitable for hashing, comparisons, etc.

const stringify = require('fast-safe-stringify').stable;
const obj = { c: 8, b: [{z:6,y:5,x:4},7], a: 3 };
console.log(stringify(obj));

Serialization with decycler

Allows custom handling of circular references during serialization, enabling you to replace or transform circular references in the resulting JSON string.

const stringify = require('fast-safe-stringify').stable;
function replaceCircular(key, value, circular) { return circular ? '[Circular]' : value; }
const obj = {};
obj.a = obj;
console.log(stringify(obj, replaceCircular));

Other packages similar to fast-safe-stringify

json-stringify-safe

Similar to fast-safe-stringify, json-stringify-safe provides a way to safely serialize objects into JSON strings, handling circular references by replacing them with a custom string. It's a bit slower compared to fast-safe-stringify but serves a similar purpose.

flatted

Flatted is a package that serializes and deserializes JavaScript objects, including nested and circular references. Unlike fast-safe-stringify, which returns a JSON string, Flatted returns a flattened string representation that can be re-parsed into the original object structure, including circular references.

README

fast-safe-stringify

Safely and quickly serialize JavaScript objects

Detects circular dependencies instead of throwing (as per usual JSON.stringify usage)

Usage

var safeStringify = require('fast-safe-stringify')
var o = {a: 1}
o.o = o

console.log(safeStringify(o))
console.log(JSON.stringify(o)) //<-- throws

Benchmarks

The json-stringify-safe module supplies similar functionality with more info and flexibility.

Although not JSON, the core util.inspect method can be used for similar purposes (e.g. logging) and also handles circular references.

Here we compare fast-safe-stringify with these alternatives:

inspectBench*10000: 132.456ms
jsonStringifySafeBench*10000: 67.382ms
fastSafeStringifyBench*10000: 31.672ms

inspectDeepBench*10000: 1632.687ms
jsonStringifySafeDeepBench*10000: 1062.449ms
fastSafeStringifyDeepBench*10000: 177.926ms

fast-safe-stringify is 2x faster for small objects, and 6x faster for large objects than json-stringify-safe.

fast-safe-stringify is 4x faster for small objects, and 9x faster for large objects than util.inspect.

Acknowledgements

Sponsored by nearForm

License

MIT