Package Exports

fast-safe-stringify

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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))  // '{"a":1,"o":"[Circular]"}'
console.log(JSON.stringify(o)) //<-- throws

toJSON support

fast-safe-stringify would not attempt to detect circular dependencies on objects that have a toJSON function. If you need to do that, you will need to attach a toJSON.forceDecirc = true property, like so:

var obj = {
  toJSON: function () {
    // something here..
    return { something: 'else' }
  }
}
obj.toJSON.forceDecirc = true

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: 44.441ms
jsonStringifySafeBench*10000: 38.324ms
fastSafeStringifyBench*10000: 25.165ms

inspectCircBench*10000: 66.541ms
jsonStringifyCircSafeBench*10000: 37.949ms
fastSafeStringifyCircBench*10000: 33.801ms

inspectDeepBench*10000: 377.053ms
jsonStringifySafeDeepBench*10000: 658.650ms
fastSafeStringifyDeepBench*10000: 268.092ms

inspectDeepCircBench*10000: 351.387ms
jsonStringifySafeDeepCircBench*10000: 695.964ms
fastSafeStringifyDeepCircBench*10000: 256.660ms

Protip

Whether you're using fast-safe-stringify or json-stringify-safe if your use case consists of deeply nested objects without circular references the following pattern will give you best results:

var fastSafeStringify = require('fast-safe-stringify')
function tryStringify (obj) {
  try { return JSON.stringify(obj) } catch (_) {}
}
var str = tryStringify(deep) || fastSafeStringify(deep)

If you're likely to be handling mostly shallow or one level nested objects, this same pattern will degrade performance - it's entirely dependant on use case.

JSON.stringify options

JSON.stringify's replacer and space options are not supported. Any value other than 0 for space halves the speed, and providing a replacer function can result in a segfault. Given that the primary focus of this serializer is speed, the trade offs for supporting these options are not desirable.

Acknowledgements

License

MIT