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# fast-safe-stringify
Safely and quickly serialize JavaScript objects
Detects circular dependencies instead of throwing (as per usual `JSON.stringify`
usage)
## Usage
```js
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:
```js
var obj = {
toJSON: function () {
// something here..
return { something: 'else' }
}
}
obj.toJSON.forceDecirc = true
```
## Benchmarks
The [json-stringify-safe](http://npm.im/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:
```js
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
Sponsored by [nearForm](http://nearform.com)
## License
MIT