Package Exports

fast-json-stringify

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Readme

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: 'mail@example.com'
}

console.log(stringify(obj)) // '{"mail":"mail@example.com"}'

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