fast-json-stringify

fast-json-stringify  

fast-json-stringify is x1-5 times faster than JSON.stringify(). It is particularly suited if you are sending small JSON payloads, the advantages reduces on large payloads.

Benchmarks:

JSON.stringify array x 3,500 ops/sec ±0.91% (85 runs sampled)
fast-json-stringify array x 4,456 ops/sec ±1.68% (87 runs sampled)
JSON.stringify long string x 13,395 ops/sec ±0.88% (91 runs sampled)
fast-json-stringify long string x 95,488 ops/sec ±1.04% (90 runs sampled)
JSON.stringify short string x 5,059,316 ops/sec ±0.86% (92 runs sampled)
fast-json-stringify short string x 12,219,967 ops/sec ±1.16% (91 runs sampled)
JSON.stringify obj x 1,763,980 ops/sec ±1.30% (88 runs sampled)
fast-json-stringify obj x 5,085,148 ops/sec ±1.56% (89 runs sampled)

Example

const fastJson = require('fast-json-stringify')
const stringify = fastJson({
  title: 'Example Schema',
  type: 'object',
  properties: {
    firstName: {
      type: 'string'
    },
    lastName: {
      type: 'string'
    },
    age: {
      description: 'Age in years',
      type: 'integer'
    },
    reg: {
      type: 'string'
    }
  }
})

console.log(stringify({
  firstName: 'Matteo',
  lastName: 'Collina',
  age: 32,
  reg: /"([^"]|\\")*"/
}))

API

fastJsonStringify(schema)

Build a stringify() function based on jsonschema.

Supported types:

• 'string'
• 'integer'
• 'number'
• 'array'
• 'object'
• 'boolean'
• 'null'

And nested ones, too.

Specific use cases

Instance	Serialized as
Date	string via toISOString()
RegExp	string

Required

You can set specific fields of an object as required in your schema, by adding the field name inside the required array in your schema.
Example:

const schema = {
  title: 'Example Schema with required field',
  type: 'object',
  properties: {
    nickname: {
      type: 'string'
    },
    mail: {
      type: 'string'
    }
  },
  required: ['mail']
}

If the object to stringify has not the required field(s), fast-json-stringify will throw an error.

Missing fields

If a field is present in the schema (and is not required) but it is not present in the object to stringify, fast-json-stringify will not write it in the final string.
Example:

const stringify = fastJson({
  title: 'Example Schema',
  type: 'object',
  properties: {
    nickname: {
      type: 'string'
    },
    mail: {
      type: 'string'
    }
  },
  required: ['mail']
})

const obj = {
  mail: '[e-mail]'
}

console.log(stringify(obj)) // '{"mail":"[e-mail]"}'

Pattern properties

fast-json-stringify supports pattern properties as defined inside JSON schema.
patternProperties must be an object, where the key is a valid regex and the value is an object, declared in this way: { type: 'type' }.
patternProperties will work only for the properties that are not explicitly listed in the properties object.
Example:

const stringify = fastJson({
  title: 'Example Schema',
  type: 'object',
  properties: {
    nickname: {
      type: 'string'
    }
  },
  patternProperties: {
    'num': {
      type: 'number'
    },
    '.*foo$': {
      type: 'string'
    }
  }
})

const obj = {
  nickname: 'nick',
  matchfoo: 42,
  otherfoo: 'str'
  matchnum: 3
}

console.log(stringify(obj)) // '{"nickname":"nick","matchfoo":"42","otherfoo":"str","matchnum":3}'

Acknowledgements

This project was kindly sponsored by nearForm.

License

MIT