fast-stringify

fast-stringify

A tiny, blazing fast stringifier that safely handles circular objects.

The fastest way to stringify an object will always be the native JSON.stringify, but it does not support circular objects out of the box. If you need to stringify objects that have circular references, fast-stringify is there for you! It has a simple API to allow for several use-cases that JSON.stringify does not while also maintaining blazing fast performance compared to its peers.

Table of contents

• fast-stringify
  • Table of contents
  • Usage
    • stringify
  • Importing
  • Benchmarks
    • Simple objects
    • Complex objects
    • Circular objects
    • Special objects
    • Stable objects
    • Stable circular objects

Usage

import { stringify } from 'fast-stringify';

const object = {
  foo: 'bar',
  deeply: {
    recursive: {
      object: {},
    },
  },
};

object.deeply.recursive.object = object.deeply.recursive;

console.log(stringify(object));
// {"foo":"bar","deeply":{"recursive":{"object":"[ref=.deeply.recursive]"}}}

stringify

interface Options {
  circularReplacer?: (key: string, value: any, referenceKey: string) => any;
  indent?: number | string;
  replacer?: (key: string, value: any) => any;
  stable?: boolean;
  stabilizer?: (
    entryA: { key: string; value: any },
    entryB: { key: string; value: any },
    stabilizerOptions: { get: (key: string) => any },
  ) => any;
}

function stringify(value: undefined | symbol | ((...args: any[]) => any), options?: Options): undefined;
function stringify<Value>(value: Value, options?: Options): string;

Stringifies the object passed based on the options passed. The only required value is the value. The additional optons passed will customize how the string is compiled. Available options:

• replacer => function to customize how the non-circular value is stringified (see the documentation for JSON.stringify for more details)
• indent => white space used to indent the stringified object for pretty-printing, either as a number of spaces or as the literal string to indent with (see the documentation for JSON.stringify for more details)
• circularReplacer => function to customize how the circular value is stringified (defaults to [ref=##] where ## is the referenceKey)

  • referenceKey is a dot-separated key list reflecting the nested key the object was originally declared at

  • keys that would be ambiguous left bare, because they are empty or contain a ., ", or \, are quoted as JSON strings, so the path always identifies exactly one value:

    stringify(nested); // {"x":{"y":{"z":{"back":"[ref=.x.y]"}}}}
    stringify(dotted); // {"x.y":{"z":{"back":"[ref=.\"x.y\"]"}}}

• stable => whether to sort the keys for stability
  • keys are sorted in ascending order by UTF-16 code unit, matching the default Array.prototype.sort ordering. Locale-aware comparison is deliberately not used, because it would make output vary between environments.
• stabilizer => function to customize how the stable object is sorted (only applies when stable is true)

stringify returns undefined rather than a string when value itself is not serializable, which is the case for undefined, functions, and symbols. Non-serializable values nested within value always produce a string: keys on objects are omitted, and entries in arrays become null.

Importing

// ESM
import { stringify } from 'fast-stringify';

// CommonJS
const { stringify } = require('fast-stringify');

Benchmarks

Simple objects

┌────────────────────────────┬─────────┬─────────────────┐
│ (index)                    │ Ops/sec │ Margin of error │
├────────────────────────────┼─────────┼─────────────────┤
│ fast-stringify             │ 1385041 │ '± 0.01%'       │
│ faster-stable-stringify    │ 1036269 │ '± 0.02%'       │
│ fast-json-stable-stringify │ 1025641 │ '± 0.02%'       │
│ json-stringify-safe        │ 840336  │ '± 0.02%'       │
│ json-stable-stringify      │ 713266  │ '± 0.02%'       │
│ decircularize              │ 468823  │ '± 0.03%'       │
│ superjson                  │ 272034  │ '± 0.03%'       │
│ json-cycle                 │ 6976    │ '± 0.09%'       │
└────────────────────────────┴─────────┴─────────────────┘
Fastest was "fast-stringify".

Complex objects

┌────────────────────────────┬─────────┬─────────────────┐
│ (index)                    │ Ops/sec │ Margin of error │
├────────────────────────────┼─────────┼─────────────────┤
│ fast-stringify             │ 227583  │ '± 0.05%'       │
│ fast-json-stable-stringify │ 193535  │ '± 0.05%'       │
│ faster-stable-stringify    │ 176553  │ '± 0.06%'       │
│ json-stringify-safe        │ 142146  │ '± 0.07%'       │
│ json-stable-stringify      │ 112246  │ '± 0.08%'       │
│ decircularize              │ 61656   │ '± 0.10%'       │
│ superjson                  │ 42057   │ '± 0.11%'       │
│ json-cycle                 │ 1038    │ '± 0.62%'       │
└────────────────────────────┴─────────┴─────────────────┘
Fastest was "fast-stringify".

Circular objects

┌────────────────────────────┬─────────┬─────────────────┐
│ (index)                    │ Ops/sec │ Margin of error │
├────────────────────────────┼─────────┼─────────────────┤
│ fast-stringify             │ 174703  │ '± 0.04%'       │
│ fast-json-stable-stringify │ 151906  │ '± 0.07%'       │
│ faster-stable-stringify    │ 143843  │ '± 0.07%'       │
│ json-stringify-safe        │ 105218  │ '± 0.11%'       │
│ json-stable-stringify      │ 87382   │ '± 0.07%'       │
│ decircularize              │ 52408   │ '± 0.10%'       │
│ superjson                  │ 30303   │ '± 0.13%'       │
│ json-cycle                 │ 972     │ '± 0.20%'       │
└────────────────────────────┴─────────┴─────────────────┘
Fastest was "fast-stringify".

Special objects

┌────────────────────────────┬─────────┬─────────────────┐
│ (index)                    │ Ops/sec │ Margin of error │
├────────────────────────────┼─────────┼─────────────────┤
│ fast-stringify             │ 81506   │ '± 0.05%'       │
│ json-stringify-safe        │ 54552   │ '± 0.09%'       │
│ fast-json-stable-stringify │ 51421   │ '± 0.10%'       │
│ faster-stable-stringify    │ 47982   │ '± 0.10%'       │
│ json-stable-stringify      │ 34450   │ '± 0.11%'       │
│ decircularize              │ 20153   │ '± 0.13%'       │
│ superjson                  │ 14992   │ '± 0.16%'       │
│ json-cycle                 │ 384     │ '± 0.11%'       │
└────────────────────────────┴─────────┴─────────────────┘
Fastest was "fast-stringify".

Stable objects

┌────────────────────────────┬─────────┬─────────────────┐
│ (index)                    │ Ops/sec │ Margin of error │
├────────────────────────────┼─────────┼─────────────────┤
│ fast-json-stable-stringify │ 699300  │ '± 0.03%'       │
│ faster-stable-stringify    │ 679347  │ '± 0.04%'       │
│ fast-stringify             │ 580383  │ '± 0.03%'       │
│ json-stable-stringify      │ 415454  │ '± 0.04%'       │
└────────────────────────────┴─────────┴─────────────────┘
Fastest was "fast-json-stable-stringify".

Stable circular objects

┌────────────────────────────┬─────────┬─────────────────┐
│ (index)                    │ Ops/sec │ Margin of error │
├────────────────────────────┼─────────┼─────────────────┤
│ faster-stable-stringify    │ 440722  │ '± 0.04%'       │
│ fast-json-stable-stringify │ 430848  │ '± 0.04%'       │
│ fast-stringify             │ 358166  │ '± 0.04%'       │
│ json-stable-stringify      │ 275938  │ '± 0.05%'       │
└────────────────────────────┴─────────┴─────────────────┘
Fastest was "faster-stable-stringify".