JSON Stringify Lite

A JSON library for Node.js that exports the following set of functions:

• jsonStringify()
• stableJsonStringify()

These functions prioritize performance at the expense of certain features. The serialized JSON output of these functions is identical to that of JSON.stringify() with the following exceptions:

1. When serializing strings, only quotation marks (") and backslashes (\) are escaped. As the vast majority of strings in real world usage do not include ASCII control characters or lone surrogate code points, a significant performance boost is gained by not checking for their presence. If you require this functionality, it is best to stick with JSON.stringify() or another alternative.
2. toJSON() methods are completely ignored. However, Buffer and Date objects will be transformed to represent the same output you would get from JSON.stringify().

Unlike JSON.stringify(), these functions do not have replacer or space parameters.

⚠ Note:
By default, a check will be made on all nested objects and arrays for circular references, and an Error will be thrown if one is encountered. Setting the safe parameter to false will disable this check and grant a considerable speed boost. If a circular reference is found when safe is set to false, the internal serialization function will be called recursively until the call stack size is exceeded.

Installation

npm install json-stringify-lite

API

jsonStringify(value[, safe])

Converts a JavaScript object or value to a JSON string. The following are valid data types that can be converted to JSON:

• null
• Boolean
• Number
• String
• Array
• Object
• Date**
• Buffer**

** Date and Buffer objects are serialized in a way that matches the output of their respective toJSON() methods.

Parameters

value
The value to convert to a JSON string.

safe (optional)
A boolean to indicate how circular references should be handled. If true then an Error will be thrown when a circular reference is encountered, otherwise no checks for circular references will be made. Defaults to true.

Return value

A JSON string that represents the provided value.

Exceptions

• Throws an Error if an object contains a circular reference and safe is set to true.
• Throws a TypeError if an object contains a BigInt.

const { jsonStringify } = require('json-stringify-lite');

const obj = {
  foo: 42,
  hello: 'world',
};

jsonStringify(obj);  // '{"foo":42,"hello":"world"}'

stableJsonStringify(value,[ compareFunction[, safe]])

A deterministic version of jsonStringify(). It performs the same, with the exception that object entries are sorted before being serialized. This ensures that consistent output is produced for the same input, at the cost of reduced performance.

Parameters

value
The value to convert to a JSON string.

compareFunction (optional)
A Function to determine how object entries are sorted. By default object keys are sorted alphabetically (A-Z).

safe (optional)
A boolean to indicate how circular references should be handled. If true then an Error will be thrown when a circular reference is encountered, otherwise no checks for circular references will be made. Defaults to true.

Return value

A JSON string that represents the provided value.

Exceptions

• Throws an Error if an object contains a circular reference and safe is set to true.
• Throws a TypeError if an object contains a BigInt.

const { stableJsonStringify } = require('json-stringify-lite');

const obj = {
  b: 'foo',
  c: 'bar',
  a: 'baz',
};

stableJsonStringify(obj);  // '{"a":"baz","b":"foo","c":"bar"}'

Using a comparison function

If a comparison function is provided, it works the same as JavaScript's Array.prototype.sort() method. The two arguments, a and b, represent two successive object keys. A number is returned to indicate sort order as follows:

• If a number less than 0 is returned, a will precede b.
• If a number greater than 0 is returned, b will precede a.
• If 0 is returned, the original order will be maintained.

const { stableJsonStringify } = require('json-stringify-lite');

// Sorts keys in descending alphabetical order.
function compareFunction(keyA, keyB) {
  return keyA < keyB ? 1 : -1;
}

const obj = {
  b: 'foo',
  c: 'bar',
  a: 'baz',
};

stableJsonStringify(obj);  // '{"c":"bar","b":"foo","a":"baz"}'